Supplementary Specification to API Standard 672 Packaged ...

SPECIFICATION

S-612J

November

2021

Supplementary Specification to API Standard 672 Packaged, Integrally Geared Centrifugal Air Compressors

NOTE This version (S-612J) of the

specification document provides the

justification statements for each

technical requirement, but is otherwise

identical in content to S-612.

Revision history

VERSION DATE PURPOSE

1.1 November 2021 Issued for Public Review

1.0 November 2018 First Edition

Acknowledgements

This IOGP Specification was prepared by a Joint Industry Programme 33 Standardization of Equipment Specifications for Procurement organized by IOGP with support by the World Economic Forum (WEF).

Disclaimer

Whilst every effort has been made to ensure the accuracy of the information contained in this publication, neither IOGP nor any of its Members past present or future warrants its accuracy or will, regardless of its or their negligence, assume liability for any foreseeable or unforeseeable use made thereof, which liability is hereby excluded. Consequently, such use is at the recipient’s own risk on the basis that any use by the recipient constitutes agreement to the terms of this disclaimer. The recipient is obliged to inform any subsequent recipient of such terms.

Please note that this publication is provided for informational purposes and adoption of any of its recommendations is at the discretion of the user. Except as explicitly stated otherwise, this publication must not be considered as a substitute for government policies or decisions or reference to the relevant legislation relating to information contained in it.

Where the publication contains a statement that it is to be used as an industry standard, IOGP and its Members past, present, and future expressly disclaim all liability in respect of all claims, losses or damages arising from the use or application of the information contained in this publication in any industrial application.

Any reference to third party names is for appropriate acknowledgement of their ownership and does not constitute a sponsorship or endorsement.

Copyright notice

The contents of these pages are © International Association of Oil & Gas Producers. Permission is given to reproduce this report in whole or in part provided (i) that the copyright of IOGP and (ii) the sources are acknowledged. All other rights are reserved. Any other use requires the prior written permission of IOGP.

These Terms and Conditions shall be governed by and construed in accordance with the laws of England and Wales. Disputes arising here from shall be exclusively subject to the jurisdiction of the courts of England and Wales.


Page 1 of 37 S-612J November 2021

Foreword

This specification was prepared under Joint Industry Programme 33 (JIP33) "Standardization of Equipment Specifications for Procurement" organized by the International Oil & Gas Producers Association (IOGP) with the support from the World Economic Forum (WEF). Companies from the IOGP membership participated in developing this specification to leverage and improve industry level standardization globally in the oil and gas sector. The work has developed a minimized set of supplementary requirements for procurement, with life cycle cost in mind, resulting in a common and jointly agreed specification, building on recognized industry and international standards.

Recent trends in oil and gas projects have demonstrated substantial budget and schedule overruns. The Oil and Gas Community within the World Economic Forum (WEF) has implemented a Capital Project Complexity (CPC) initiative which seeks to drive a structural reduction in upstream project costs with a focus on industry-wide, non-competitive collaboration and standardization. The CPC vision is to standardize specifications for global procurement for equipment and packages. JIP33 provides the oil and gas sector with the opportunity to move from internally to externally focused standardization initiatives and provide step change benefits in the sector's capital projects performance.

This specification has been developed in consultation with a broad user and supplier base to realize benefits from standardization and achieve significant project and schedule cost reductions.

The JIP33 work groups performed their activities in accordance with IOGP's Competition Law Guidelines (November 2020).



Table of Contents

Foreword .................................................................................................................................................. 1

Introduction ............................................................................................................................................... 3

1 Scope ....................................................................................................................................................... 5

2 Normative References .............................................................................................................................. 5

3 Terms, Definitions, Acronyms, and Abbreviations ................................................................................... 6

3.1 Terms and Definitions .................................................................................................................... 6

6 Basic Design ............................................................................................................................................. 7

6.1 General ........................................................................................................................................... 7

6.2 Pressure Casings ......................................................................................................................... 10

6.3 Casing Connections ..................................................................................................................... 11

6.5 Rotating Elements ........................................................................................................................ 11

6.8 Bearings and Bearing Housings................................................................................................... 12

6.10 Materials ....................................................................................................................................... 14

7 Accessories ............................................................................................................................................ 17

7.1 Drivers .......................................................................................................................................... 17

7.2 Couplings and Guards ................................................................................................................. 20

7.3 Baseplate/Support Structure ........................................................................................................ 21

7.4 Controls and Instrumentation ....................................................................................................... 22

7.5 Piping ........................................................................................................................................... 28

7.6 Intercoolers, Aftercoolers and Other Pressure Equipment .......................................................... 31

7.7 Inlet Air Filter and Silencer ........................................................................................................... 33

7.9 Special Tools and Spare Parts..................................................................................................... 33

8 Inspection, Testing and Preparation for Shipment ................................................................................. 33

8.3 Testing .......................................................................................................................................... 33

8.4 Preparation for Shipment ............................................................................................................. 35

Bibliography ............................................................................................................................................ 37

List of Tables

Table 2—Material Selection.............................................................................................................................. 15

Table 1—Equipment Monitoring ....................................................................................................................... 26



Introduction

The purpose of this specification is to define a minimum common set of requirements for the procurement of packaged, integrally geared centrifugal air compressors in accordance with API Standard 672, 5th Edition, August 2019, Packaged, Integrally Geared Centrifugal Air Compressors for Petroleum, Chemical, and Gas Industry Services for application in the petroleum and natural gas industries.

This specification follows a common document structure comprising the four documents as shown below, which together with the purchase order define the overall technical specification for procurement.

JIP33 Specification for Procurement Documents Supplementary Technical Specification

This specification is to be applied in conjunction with the supporting procurement data sheet, information requirements specification (IRS) and quality requirements specification (QRS) as follows.

IOGP S-612: Supplementary Specification to API Standard 672 Packaged, Integrally Geared Centrifugal Air Compressors

This specification defines the technical requirements for the supply of the equipment and is written as an overlay to API Standard 672, following the API Standard 672 clause structure. Clauses from API Standard 672 not amended by this specification apply as written to the extent applicable to the scope of supply.

Modifications to API Standard 672 defined in this specification are identified as Add (add to clause or add new clause), Replace (part of or entire clause) or Delete.

IOGP S-612D: Procurement Data Sheet for Packaged, Integrally Geared Centrifugal Air Compressors

The procurement data sheet defines application specific requirements, attributes and options specified by the purchaser for the supply of equipment to the technical specification. The procurement data sheet may also include fields for supplier provided information attributes subject to purchaser’s technical evaluation. Additional purchaser supplied documents may also be incorporated or referenced in the procurement data sheet to define scope and technical requirements for enquiry and purchase of the equipment.



IOGP S-612L: Information Requirements for Packaged, Integrally Geared Centrifugal Air Compressors

The IRS defines the information requirements, including contents, format, timing and purpose to be provided by the supplier. It may also define specific conditions which invoke information requirements.

IOGP S-612Q: Quality Requirements for Packaged, Integrally Geared Centrifugal Air Compressors

The QRS defines quality management system requirements and the proposed extent of purchaser conformity assessment activities for the scope of supply. Purchaser conformity assessment activities are defined through the selection of one of four generic conformity assessment system (CAS) levels on the basis of evaluation of the associated service and supply chain risks. The applicable CAS level is specified by the purchaser in the data sheet or in the purchase order.

The terminology used within this specification and the supporting procurement data sheet, IRS and QRS follows that of API Standard 672 and is in accordance with ISO/IEC Directives, Part 2 as appropriate.

The procurement data sheet and IRS are published as editable documents for the purchaser to specify application specific requirements. The supplementary specification and QRS are fixed documents.

The order of precedence (highest authority listed first) of the documents shall be:

a) regulatory requirements;

b) contract documentation (e.g. purchase order);

c) purchaser defined requirements (procurement data sheet, IRS, QRS);

d) this specification;

e) API Standard 672.



1 Scope

1.1

Add to section

This specification covers constant speed electric motor driven integrally geared centrifugal air compressor, with a shaft power range of up to 1,500 kW, for plant and instrument air application.

NOTE This specification can also be applied to steam turbine driven air compressor packages. However, the requirements for the steam turbine driver are not covered within this specification.

Justification

This power range covers most applications for plant and instrument air supply.

1.2

Add to section

This specification applies to spared basic duty packages.

Justification

Basic duty packages are suitable for plant and instrument air supply with a standby unit.

2 Normative References

Add to section

API Recommended Practice 687:2015, Rotor Repair

ASME B1.20.1, Pipe Threads, General Purpose, Inch

ASME BTH-1, Design Of Below-The-Hook Lifting Devices

ASTM A105/A105M, Standard Specification for Carbon Steel Forgings for Piping Applications

ASTM A350/A350M, Standard Specification for Carbon and Low-Alloy Steel Forgings, Requiring Notch Toughness Testing for Piping Components

BS 4235-1, Specification for Metric Keys and Keyways - Part 1: Parallel and Taper Keys

EN 1993-1-8, Eurocode 3: Design of steel structures - Part 1-8: Design of joints

EN 13445, Unfired pressure vessels

IEC 60034-1, Rotating Electrical Machines – Part 1: Rating and Performance

IEC 61043, Electroacoustic – Instruments for the measurement of sound Intensity – Measurements with pairs of pressure sensing microphone

IOGP S-703, Supplementary Specification to IEC 60034-1 Low Voltage Three Phase Cage Induction Motors

IOGP S-704, Supplementary Specification to IEC 60034-1 High Voltage Three-phase Cage Induction Motors

IOGP S-710, Supplementary Specification to API Standard 661 Air-cooled Heat Exchangers



IOGP S-715, Supplementary Specification to NORSOK M-501 Coating and Painting for Offshore, Marine, Coastal and Subsea Environments

IOGP S-717, Supplementary Specification to ISO 15664 Noise Emitting Equipment

IOGP S-733D, Data Sheet for Low Voltage Motors (IEEE Std 841)

ISO 281, Rolling bearings — Dynamic load ratings and rating life

ISO 4406, Hydraulic fluid power — Fluids — Method for coding the level of contamination by solid particles

ISO 2151, Acoustics — Noise test code for compressors and vacuum pumps — Engineering method (Grade 2)

ISO 9614-2, Acoustics — Determination of sound power levels of noise sources using sound intensity — Part 2: Measurement by scanning

ISO 12944-2, Paints and varnishes — Corrosion protection of steel structures by protective paint systems — Part 2: Classification of environments

ISO 12944-5, Paints and varnishes — Corrosion protection of steel structures by protective paint systems — Part 5: Protective paint systems

ISO 12944-6, Paints and varnishes — Corrosion protection of steel structures by protective paint systems — Part 6: Laboratory performance test methods

ISO 12944-9, Paints and varnishes — Corrosion protection of steel structures by protective paint systems — Part 9: Protective paint systems and laboratory performance test methods for offshore and related structures

ISO 14691, Petroleum, petrochemical and natural gas industries — Flexible couplings for mechanical power transmission — General-purpose applications

ISO 20816, Mechanical vibration — Measurement and evaluation of machine vibration

ISO 21457, Petroleum, petrochemical and natural gas industries - Materials selection and corrosion control for oil and gas production systems.

ISO 21940-11, Mechanical vibration — Rotor balancing — Part 11: Procedures and tolerances for rotors with rigid behaviour

ISO 21940-32, Mechanical vibration — Rotor balancing — Part 32: Shaft and fitment key convention

SAE AS4059, Aerospace Fluid Power - Cleanliness Classification for Hydraulic Fluids

3 Terms, Definitions, Acronyms, and Abbreviations

3.1 Terms and Definitions

Add new term

3.1.59 undesirable speeds Critical speeds up to three times the operating speed of shaft.

Add new term

3.1.60 carbon steel



Alloy of carbon and iron containing up to 2 % mass fraction carbon and up to 1.65 % mass fraction manganese and residual quantities of other elements, except those intentionally added in specific quantities for deoxidation (usually silicon and/or aluminium).

Add new term

3.1.61 low alloy steel Steel containing a total alloying element content of less than 5 % mass fraction, or steels with less than 10.5 % mass fraction chromium, but more than that specified for carbon steel.

Add new term

3.1.62

cast iron Iron-carbon alloy containing approximately 2 % to 4 % mass fraction carbon.

6 Basic Design

6.1 General

6.1.3 Sound Pressure Level

Add new section

6.1.3.4 Sound pressure level shall be measured at 1.0 m (3.3 ft) from the skid boundary.

Justification

States applicable noise test method. Noise acceptance tests can be unrepresentative if not conducted correctly.

Add new section

6.1.3.5 Sound pressure level measurements shall be taken at 1.0 m (3.3 ft) from the discharge blow-off silencer outlet, if specified.

Justification

Noise acceptance tests can be unrepresentative if not conducted correctly. The blow-off silencer test may be required depending on it's availability for the test.

6.1.4 Packaged Equipment

Replace list item b) with

b) main drive coupling and coupling guard;

Justification

Coupling is required to transmit power from driver to compressor. Guard is required to prevent injury to operation and maintenance personnel.

Replace list item c) with

c) skid baseplate with lifting lugs;



Justification

Enables equipment to be mounted, assembled, tested and installed as a package unit reducing site interfaces with consequent reduction in cost and schedule.

Replace list item e) with

e) common lube oil system for compressor, gear and driver, including mist eliminator and lube oil heater;

Justification

Lube oil system is required for proper lubrication of compressor, gear and driver.

Replace list item f) with

f) control, monitoring and protection instruments with on-skid instruments,

Justification

Required for control, monitoring and protection of the compressor package.

Replace list item g) with

g) control panel, control, signal and power cables, and junction box;

Justification

The control, monitoring and protection instruments are justified for safety, operability and equipment monitoring purposes.

Replace list item h) with

h) main driver;

Justification

Required to drive the compressor.

Replace list item i) with

i) inlet air filter with weather hood and support leg;

Justification

Filter to provide clean air and hood to prevent rain from entering air supply system.

Replace list item j) with

j) variable inlet guide vane;

Justification

Provides energy efficient capacity control.

Replace list item k) with

k) on-skid interconnecting piping, fitting and valves, including control valves and pressure relief valves;



Justification

The piping, fittings, valves, and PRV's are required for interconnections and proper safety and control.

Add new list item q)

q) air inlet silencer;

Justification

Required to meet the noise level threshold.

Add new list item r)

r) local emergency stop push button;

Justification

Safety feature.

Add new list item s)

s) blow-off line expansion joint for off-skid blow-off valve and silencer;

Justification

To avoid excessive nozzle loads on Purchaser's interconnecting pipework due to thermal expansion.

Add new list item t)

t) compressor gear box breather and screen.

Justification

Breather is required to relieve oil vapor pressure in gear box. Screen is required to prevent oil contamination.

Add to section

For offshore installation, the compressor package shall be a complete unit installed on a single skid.

Justification

Reduces site work.

6.1.9 Performance Criteria

Add new section

6.1.9.4 The turndown capacity of the compressor shall be 15 % or more of the rated capacity.

Justification

Provides acceptable turn down capacity before stop/start is necessary.



6.1.10 Purchaser Connections

In first sentence replace "DN 12 (NPS ½)" with

DN 20 (NPS ¾)

Justification

Provides adequate mechanical strength against nozzle loads from purchaser connection.

Add to section

Nozzles for purchaser connections DN 50 (NPS 2) or larger shall be flanged in accordance with ASME B16.5.

Justification

Provides better seal for larger sized connections.

Add to section

Nozzles for purchaser connections smaller than DN 50 (NPS 2) shall be threaded in accordance with ASME B1.20.1 or flanged.

Justification

Supplier standard where threaded or flanged for these smaller connections is acceptable. Other connections are not advised.

Add to section

Proprietary connection types shall not be used for purchaser connections.

Justification

The ability to adequately service the assembly with commonly used, standardized connections.

6.1.12 Mounting Surfaces

Add to section

Shims under the driver mounting pad shall be full-face stainless steel.

Justification

Stainless steel is required for corrosion resistance. A full-face shim provides the correct minimum support to the driver.

6.2 Pressure Casings

Add new section

6.2.5 Jackscrews, guide rods, cylindrical casing-alignment dowels shall comply with 6.12.1.

Justification

To facilitate disassembly and reassembly.



Add new section

6.2.6 Counter bored or recessed faces shall comply with 6.12.1.3.

Justification

To prevent a leaking joint or improper fit caused by marring of the face.

Add new section

6.2.7 Guide rods shall conform to 6.12.1.1.

Justification

Although adopted into latest revision of parent standard in section 6.12 'Additional Requirements for Special Duty Packages' this IOGP specification only applies to basic duty packages. This requirement is considered essential irrespective of the package duty.

Add new section

6.2.8 Lifting lugs shall be in accordance with 6.12.1.2.

Justification

Although adopted into latest revision of parent standard in section 6.12 'Additional Requirements for Special Duty Packages' this IOGP specification only applies to basic duty packages. This requirement is considered essential irrespective of the package duty. Lifting lugs are required to lift top half of casing as this component is heavier than 25kg.

6.3 Casing Connections

Add new section

6.3.11 Each compressor section shall have a drain.

Justification

This allows each section of the compressor to be drained.

6.5 Rotating Elements

6.5.1 Shafts

6.5.1.2

6.5.1.2.3

Replace section with

The total combined electrical and mechanical runout shall not exceed 6 μm (0.25 mils).

Justification

Reduces the errors in monitoring. Without this the monitoring error can either increase or decrease the monitor reading from the true vibration.



6.5.1.4


Shaft keyways shall have fillet radii conforming to ASME B17.1 or BS 4235-1.

Justification

Establish common standard for keyways used in North America and Europe.

Add new section

6.5.1.5 Shaft and fitment key conventions shall be in accordance with ISO 21940-32.

Justification

Establish common standard for keyways.

6.5.2 Impellers

Add new section

6.5.2.3 The impeller construction and attachment method shall retain the impeller-to-shaft connection with a locking arrangement.

Justification

To prevent impeller loosening in service, especially during start-up, over speed, reverse rotation and surge events.

6.8 Bearings and Bearing Housings

6.8.1 Bearings—General

6.8.1.1


Pinion shaft rotors shall have hydrodynamic radial and thrust bearings or collars.

Justification

Required for increased bearing life on this high speed application.

Add to section

If approved by the purchaser, rolling element bearings may be used only for low-speed bull gear shaft rotors.

Justification

Rolling element bearing requires disassembly of bull gear from gear box and disassembly of coupling hub from bull gear shaft. Sleeve bearing doesn't require any disassembly as it can be horizontally split.

Add new section

6.8.1.4 Basic rating life for anti-friction bearing, defined by ISO 281, shall be 50,000 hours or more.



Justification

Increased bearing life reduces maintenance costs.

Add new section

6.9.7 Lubrication system design shall prime the main oil pump prior to compressor start-up.

Justification

Prevents bearing damage during startup transient.

Add new section

6.9.8 Lube Oil Cooler

6.9.8.1 Air-cooled lube oil coolers design shall be a single-bay two-fan unit.

Justification

Two fan unit increases reliability.

6.9.8.2 Air-cooled lube oil cooler design shall conform to IOGP S-710.

Justification

Minimum acceptable common standard.

6.9.8.3 Air-cooled lube oil cooler header box design shall be removable cover plate or plug type construction.

Justification

Minimum acceptable common standard.

Add new section

6.9.9 Lube Oil Filter

6.9.9.1 Lube oil filter system shall have dual filters.

Justification

Increased reliability.

6.9.9.2 Each lube oil filter shall be sized for at least 100 % of the flow.

Justification

Increased reliability.

6.9.9.3 Lube oil filters shall be designed for on-line change-over and on-line replacement of the off-line unit.

Justification

Increased reliability and ease of maintenance.



6.9.9.4 Lube oil filters shall be equipped with a differential pressure local indicating transmitter.

Justification

Facilitates planned maintenance.

Add new section

6.9.10 Lube Oil Reservoir

6.9.10.1 Lube oil reservoir capacity retention time shall be 3 minutes or greater.

Justification

Extends the life of the compressor bearings.

6.9.10.2 The lube oil reservoir shall have a temperature-controlled electric immersion heater.

Justification

Maintains viscosity limit of oil in low ambient temperature and drives off moisture.

6.10 Materials

Add new section

6.10.5 Material Selection

6.10.5.1 Material selection philosophy shall be in accordance with the recommendations and guidelines of ISO 21457, unless specified in Table 2.

Justification

Provides common standard for material selection.



Table 2—Material Selection

Item Material of construction (harsh environment) b

Diffuser Manufacturer’s standard Stainless steel

Inlet Air Filter/Silencer Carbon steel (hot dip galvanized) 316 stainless steel

Intercooler/ Aftercooler (Water Cooled) c

Shell Carbon steel or cast iron (coated) Carbon steel or cast iron (coated) or 316 stainless steel

Tube 316 stainless steel or 90/10 Cu-Ni or admiralty brass

316 stainless steel or 90/10 Cu-Ni or admiralty brass

Tube sheet / Baffle Compatible with the tube material Compatible with the tube material

Intercooler/ Aftercooler/ Lube Oil Cooler (Air Cooled) c

Tube Carbon steel with aluminium fins 316 stainless steel

Tube sheet / Header Box/ Tube Support

Carbon steel (coated) 316 stainless steel

Lube Oil System Components

Lube Oil Cooler c

Shell Carbon steel 316 stainless steel

Tube 90/10 Cu-Ni or admiralty brass 90/10 Cu-Ni or admiralty brass

Tube sheet Brass Brass

Lube Oil Reservoir Carbon steel (coated) 316 stainless steel

Lube Oil Piping Carbon steel 316 stainless steel

Lube Oil Piping

(downstream of lube oil filter) Stainless steel 316 stainless steel

Lube Oil Filter Carbon steel (coated) 316 stainless steel

Piping, Tubing and Miscellaneous Items

Air / Cooling Water Piping Carbon steel (coated)

Tubing and fittings 316 stainless steel 316 stainless steel

Blow-off Silencer housing Carbon steel (hot dip galvanized) 316 stainless steel

Blow-off Silencer internals 316 stainless steel 316 stainless steel

Base Fames Carbon steel (coated or hot dip galvanized)

Carbon steel (coated or hot dip galvanized)

Instrument Housing Stainless steel or aluminium 316 stainless steel or aluminium

Junction Box Carbon steel (hot dip galvanized) or 304 stainless steel or aluminium

316 stainless steel or aluminium

Noise Enclosure Carbon steel (coated) Carbon steel (coated)

Local Control Cabinet Carbon steel (coated) Carbon steel (coated)

a Base case applies to atmospheric corrosion category C1 to C3 (low to medium corrosivity) defined by ISO 12944-2. b Harsh environments applies to corrosion category C4 to CX (high to extreme corrosivity) defined by ISO 12944-2. c Cooling water is assumed to be fresh water or glycol-water mixture.



Add new section

6.10.6 Coating

6.10.6.1 Onshore and non-marine coating systems shall be selected in accordance with ISO 12944-5.

Justification

For onshore, Part 5 provides guidelines for minimum coating system selection incl. required surface preparation based on the specified durability and corrosivity and already includes mandatory references to Part 1,2,4.

6.10.6.2 Offshore and marine coastal coating systems shall be in accordance with ISO 12944-9 or IOGP S-715.

Justification

Provides a common standard.

6.10.6.3 Cast iron, carbon steel and low alloy steel external surfaces shall be coated.

Justification

Extends life of equipment.

6.10.6.4 Bearings, seals, flange mating faces, instrument face, instrument cases, cable trays and cables, shafts, polished or machined surfaces, control valve stems, nameplates and item tags shall not be coated.

Justification

These components are not coated as they are either made from corrosion resistant material or protected by insulation (cables), gaskets (flange mating surfaces) or lubricated (bearings and seals).

6.10.6.5 Stainless steel equipment items and piping shall be coated when operating at a temperature exceeding 60 °C (140 °F) in a marine atmosphere.

Justification

Extends life of equipment. Stainless steel corrosion resistance reduces at temperatures above 60 °C in a marine atmosphere.

6.10.6.6 Bearings, seals, flange mating faces, instrument faces, instrument cases, cable trays and cables, shafts, polished or machined surfaces, control valve stems, nameplates and item tags shall be protected from blasting and coating being applied to adjacent equipment.

Justification

Protects these components from damage.

6.10.6.7 Insulated stainless steel equipment and piping shall be coated.

Justification

Stainless steel corrosion resistance is reduced when covered by insulation due to entrapment of moisture, regardless of temperature. Difficult to inspect equipment under insulation and corrosion may go unnoticed.

6.10.6.8 Coating under insulation shall be in accordance with IOGP S-715.



Justification

IOGP S-715 is needed to mitigate risk of corrosion under insulation.

6.10.6.9 Onshore and non-marine coating systems shall be qualified to ISO 12944-6.

Justification

ISO 12944-6 provides minimum qualification testing requirements for onshore coating.

7 Accessories

7.1 Drivers

7.1.1 General

7.1.1.5

Delete "If specified,"

Justification

Allows for drop in compressor and driver efficiencies due to wear and test tolerances.

7.1.2 Electric Motors

7.1.2.1

Delete section

Justification

Transferred to data sheet selection.

7.1.2.1.3


For general outdoor environments, motors shall have a minimum ingress protection class of IP55.

Justification

Provides a common standard for weather protection of motors.

7.1.2.1.4

Replace section (including note) with

For environments with areas exposed to powerful water jets and deluge or offshore open deck, motors shall have a minimum ingress protection class of IP56.

Justification

Provides a common standard for weather protection of motors exposed to harsh environments.



Add new section

7.1.2.1.5 Motors shall be supplied with a minimum of Class F insulation.

Justification

Provides a common standard for electrical insulation of motors.

Add new section

7.1.2.1.6 The main driver motor shall be provided with stator winding anti-condensation type space heater.

Justification

Prevents damaging condensation.

Add new section

7.1.2.1.7 The stator winding space heater shall remain energized when the main drive motor is not running.

Justification

Prevents condensation inside motor when it is not running.

Add new section

7.1.2.1.8 Motors with sleeve bearings shall be equipped with one x and one y radial proximity probes per bearing.

Justification

Provides a consistent method for condition monitoring of motor bearings in accordance with API-672.

Add new section

7.1.2.1.9 Lube oil for motors equipped with sleeve bearings shall be fed through the common pressurized lube oil system used by the compressor and gearing.

Justification

Provides a common lube oil system reducing space and weight. Reduces points of failure therefore increases reliability and a common industry solution.

Add new section

7.1.2.1.10 Motor equipped with sleeve bearings shall have one dual element bearing metal resistance temperature detector per bearing.

Justification

This provides temperature monitoring with redundancy. Should one element fail it would be difficult to replace.

Add new section

7.1.2.1.11 Medium voltage motors shall have a minimum of two embedded 3-wire Pt100 resistance temperature detectors for windings per each phase of stator windings.



Justification

Provides a need for each electrical phase to be monitored and protected from over heating due to a malfunction e.g. damaged insulation.

Add new section

7.1.2.1.12 Bearing and winding resistance temperature detectors shall have a local display for temperature readings.

Justification

Provides a local display to facilitate maintenance.

Add new section

7.1.2.3 Electric Motor Testing

7.1.2.3.1 When low-voltage motors less than 600 volts have been type tested in accordance with IEC 60034-1, routine tests may be omitted.

Justification

Mass produced low voltage motors are already type tested to an acceptable standard such as IEC 60034-1:2017, 9.1 or equivalent standard.

7.1.2.3.2 Medium voltage motors shall be no-load tested.

Justification

These motors have higher power ratings than low voltage motors which results in a greater power demand, so it is important to verify the motor no-load losses and locked rotor current.

7.1.3.2.3 The stator-winding resistance of medium voltage motors shall be tested.

Justification

These motors have higher power ratings than low voltage motors which results in a greater power demand, so it is important to verify the motor stator winding resistance for faulty winding.

7.1.3.2.4 The insulation resistance of medium voltage motors shall be tested.

Justification

To avoid short circuits due to faulty insulation with consequential damage and possible risk of electrocution.

7.1.3.2.5 The efficiency of medium voltage motors shall be determined for 50 %, 75 % and 100 % of rated load.

Justification

It is more important than for low voltage motors to verify efficiency for these higher powered motors to reduce effect of power demand on the plant power supply.

7.1.2.3.6 The vibration of medium voltage motors shall be measured and assessed against agreed criteria in ISO 20816.



Justification

It is required to verify vibration values to avoid possible vibration damage or vibration symptoms leading to failure of the motor.

7.1.3.2.7 The phase sequencing, direction of rotation and terminal marking of medium voltage motors shall be performed.

Justification

More important to verify these values for these higher powered motors to avoid possible damage due to wrong direction of rotation.

7.1.3.2.8 The noise of medium voltage motors shall be tested.

Justification

Protect the health of personnel.

7.2 Couplings and Guards

7.2.1 Couplings

7.2.1.2

In list item d), replace "125 mm (5 in.)" with

200 mm (8 in.)

Justification

Enables maintenance to be carried out without having to adjust the position of the driver or driven equipment.

Add new list section f)

f) Flexible elements shall not be coated.

Justification

Not necessary or desirable to coat corrosion resistant alloys.

Add new list section g)

g) Coupling design and manufacture shall conform to ISO 14691.

Justification

Provides a common internationally recognized minimum standard.

7.2.1.3


The coupling assembly shall be dynamically balanced to Grade 2.5 in accordance with ISO 21940-11.



Justification

Establishes a more stringent standard than API-672 for coupling dynamic balancing and replaces ISO 1940-1:2003. API references this obsolete standard.

7.2.2 Coupling Guards

7.2.2.2

In second sentence, replace "comply with specified standards such as ANSI B11.19, ISO 14120 or other applicable nationally recognized standards." with

be in accordance with ANSI B11.19 or ISO 14120.

Justification

Provides a common internationally recognized standard for coupling guards to prevent injury to personnel.

7.3 Baseplate/Support Structure

7.3.2

Add to section

Baseplate shall be provided with a drain connection of DN 50 (NPS 2) minimum.

Justification

Minimum DN 50 drain size is adequate for drainage and less prone to vibration induced fatigue. Removes any oil spillage on baseplate which can cause injury to personnel from slipping.

Add to section

Baseplate welding shall be continuous.

Justification

Difficult to calculate and ensure sufficient strength with intermittent welding, bad for surface protection and maintenance.

Add to section

The design of baseplate lifting lugs shall be in accordance with the specified design code.

Justification

Definition of Statutory requirement which sets the basis for requirements to be followed in all structural design, such as safety factors and design codes. All contract items needs to follow this code. Codes to be followed will vary dependent on region and country location.

7.3.11

In first sentence delete "If the supported driver weighs more than 225 kg (500 lb),"

Justification

Ensures jackscrews have sufficient strength.



7.4 Controls and Instrumentation

7.4.1 General

7.4.1.5

Add to section

Interface between the local control panel and the purchaser's safety instrument system shall be through hard-wired signal interface.

Justification

Hardwired communication is more secure and reliable.

Add new section

7.4.1.8 Instrumentation and control systems shall be designed for continuous operation at the specified ambient temperature without degradation of the measurement and control accuracy specified by the manufacturer.

Justification

Establishes correct design for the specified ambient temperature.

7.4.2 Control Systems

7.4.2.1


Compressor capacity control modes shall be achieved via the specified method.

Justification

Preferred method of capacity modulation due to lower power consumption compared to inlet throttling valve method.

7.4.2.3

Add to section

When surge control is based on monitoring motor current, an additional monitoring signal based on discharge pressure or flow shall be provided.

Justification

A secondary monitoring signal directly related to process conditions provides an important supplement to the indirect measure of motor current.

Add new section

7.4.2.7 Field analogue instruments, transmitters and control valves shall be provided with the specified communication protocol.



Justification

To facilitate effective communication, remote monitoring and diagnostics from the purchaser’s control system.

Add new section

7.4.2.8 When air compressors are operating in parallel, the controller for parallel operation shall be capable of load-sharing.

Justification

Required to enable load sharing of the compressor units during parallel operation.

7.4.3 Instrument and Control Panels

7.4.3.1

Replace list item j) with

j) local and remote read-out of vibration and position data.

Justification

Provides for remote and local data monitoring and data retrieval of this critical information to prevent possible damage to compressor from high vibration.

7.4.4 Instrumentation

7.4.4.3 Thermowells

7.4.4.3.2

Replace "DN 19" with

DN 20

Justification

Correction of API 672

7.4.4.6 Vibration and Position Detectors

7.4.4.6.2

Replace second sentence with

Accelerometers shall be flush mounted, installed and calibrated in accordance with API standard 670.

Justification

Provides a common standard for accelerometers.

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7.4.4.6.3 Angular orientation of probe mounting holes shall be the same for both ends of each pinion.



Justification

This provides a consistent orientation for monitoring and protection.

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7.4.4.6.4 Thrust bearings shall have axial position monitoring with two proximity probes.

Justification

Provides greater reliability in condition monitoring of thrust bearing. For compressors with pinion shafts using only thrust collars, axial displacement probes on pinion shaft are not required.

Add new section

7.4.4.6.5 Proximity probes shall be installed to sense the shaft itself or an integral axial surface of the shaft, within an axial distance of 300 mm (12 in.) from the thrust bearing.

Justification

Avoids false measurement if shaft is not integral and prevents errors from thermal expansion.

Add new section

7.4.4.6.6 Vibration monitoring system accuracy shall be in accordance with API standard 670.

Justification

Provides common standard for level of accuracy.

Add new section

7.4.4.7 Hydrodynamic bearings shall have bearing metal temperature sensors.

Justification

Required for predictive maintenance.

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7.4.4.8 Pressure Limiting Valve and Pressure Relief Valves

7.4.4.8.1 Relief valves shall not discharge to a location within normal operation or maintenance access areas.

Justification

Provides safety to personnel. Relief valve discharges can injure personnel in these areas.

7.4.4.8.2 Radial relief valves shall have guards.

Justification

Provides safety to personnel. Prevents discharge impacting personnel.

7.4.4.8.3 Relief valve size, settings and accumulation for each compressor failure mode shall be calculated.



Justification

This provides data to verify that all modes of equipment failure have been considered.

Add new section

7.4.4.9 Gauges

7.4.4.9.1 Local gauges shall be liquid filled.

Justification

Liquid-filled gauges are required for areas subject to vibration. Prevents damage to instrument providing more accurate reading.

7.4.4.9.2 Level gauge as a minimum shall span high and low trip set points.

Justification

Provides sufficient range from the level gauge.

7.4.4.9.3 The scale on level glass or magnetic level gauges shall indicate percentage or units of length consistent with system of units used in the data sheet.

Justification

Reduces errors by using consistent system of units.

Add new section

7.4.4.10 Discharge blow-off valves shall have stainless steel internals with soft polytetrafluoroethylene (PTFE) seat.

Justification

Increases valve design life and reliability.

Add new section

7.4.4.11 Pressure transmitters shall be provided with block and bleed manifolds as specified.

Justification

Block and bleed is required for isolation of pressure transmitters.

Add new section

7.4.4.12 Control valves shall be mounted to permit servicing and disassembly without removing valve body from the line.

Justification

Facilitates maintenance.

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7.4.4.13 Mechanical switches shall not be provided.



Justification

Switches in general are not best practice due to poor reliability.

Add new section

7.4.4.14 Compression tube fittings shall be flareless, double-ferrule type.

Justification

Provides robustness and reliability of instrument tubing. Double ferrule provides tight sealing for pressures up to 6000 psig

Add new section

7.4.4.15 Tubing fittings and fitting components shall be from a single manufacturer.

Justification

Provides compatibility and reliability.

7.4.5 Alarms and Shutdowns

7.4.5.1 General

7.4.5.1.3

Table 1—Equipment Monitoring

Add new rows to Table 1

Condition Alarm Recommended Shutdown

Compressor axial position (high / high-high) X X

High motor radial vibration g (high / high-high) X X

High motor bearing temperature g (high / high-high) X X

High motor winding temperature (high/ high-high) X X

g When motor equipped with sleeve bearing



7.4.5.3.1

Delete first sentence

Justification

As units are typically spared the spare unit(s) may be brought online to permit the shutdown and test of affected unit(s) without negatively impacting system air supply.

Delete second sentence

Justification

As units are typically spared the spare unit(s) may be brought online to permit the shutdown and test of affected unit(s) without negatively impacting system air supply.

7.4.6 Electrical Systems

Add new section

7.4.6.8 Cable trays, conduits and transit frames for routing the purchaser's electrical power and control cables to the respective consumer on the skid shall be provided.

Justification

Provides cable protection and clarifies work scope interfaces between Purchaser and Supplier.

Add new section

7.4.6.9 Voltages less than 1 kV shall have a single-point electrical interface.

Justification

Reduces number of penetrations through enclosure and clarifies work scope interfaces between Purchaser and Supplier.

Add new section

7.4.6.10 Main driver motors greater than 1 kV shall have a separate electrical interface.

Justification

Separates different voltages for incoming power supplies and provides clarification of interface between Purchaser and Supplier.



7.5 Piping

7.5.1 General

7.5.1.2

Delete "If specified,"

Justification

Reduces piping interfaces between Purchaser and Supplier.

Add new section

7.5.1.8 Seal welding of galvanized pipe shall not be used.

Justification

Prevents corrosion to galvanized pipe surface due to vaporization of the coating.

Add new section

7.5.1.9 Utility piping and tubing shall be provided with single-point tie-in connection with isolation valve located at skid edge.

Justification

Reduces utility system piping interfaces between Purchaser and Supplier. Clarifies isolation valves as included in Supplier's scope.

Add new section

7.5.1.10 Drain lines shall be terminated to the edge of the baseplate with an isolation valve at the purchaser's tie-in point.

Justification

Reduces piping interfaces between Purchaser and Supplier and provides a convenient location. Clarifies isolation valves as included in Supplier's scope.

Add new section

7.5.1.11 When the minimum design temperature is less than -9.4 °C (15 °F), ASTM A105/A105M carbon steel flanges shall not be used.

Justification

To avoid brittle fracture in a low ambient temperature.

Add new section

7.5.1.12 When the minimum design temperature is less than -9.4 °C (15 °F), carbon steel flanges shall be ASTM A350/A350M Grade LF2 Class 1.



Justification

To avoid brittle fracture in a low ambient temperature.

Add new section

7.5.1.13 Slip-on flanges shall be double welded.

Justification

Provides a higher strength joint.

Add new section

7.5.1.14 The installation of permanent in-line strainers shall permit dismantling of strainer elements without removing strainer body or housing.

Justification

Facilitates maintenance.

Add new section

7.5.1.15 Expansion joints used in compressed air service shall be metallic bellows type joints.

Justification

Metallic bellows provide sufficient strength and are proven in service.

Add new section

7.5.1.16 Compressor discharge check valves shall be piston type or dual disk design in 316L stainless steel construction.

Justification

Provides common standard type for discharge check valves.

Add new section

7.5.1.17 Ball valves constructed so that the ball is held in place with a threaded portion of the valve body shall not be used, unless the valve halves are positively secured together by seal welding by the valve manufacturer.

Justification

Prevents failure due to wear of the threaded joint.

Add new section

7.5.1.18 Quarter turn block valves in isolation services shall have a locking mechanism capable of accepting a car seal or pad lock.



Justification

For the purpose of locking or car-sealing the valve in its intended position.

Add new section

7.5.1.19 Valve stems and valve shafts shall be designed for stem retention.

Justification

Blow-outs can occur if: a. The stem or shaft becomes separated from the closure device b. The stem nut becomes detached from the yoke c. The packing gland is removed. These events will be avoided by including safety features in the design of the valve.

Add new section

7.5.1.20 The weakest link of the valve stem design shall be outside of the pressure boundary.

Justification

Prevent blowouts.

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7.5.1.21 The anti blow-out stem retention configuration shall be located internally to the valve.

Justification

Safety risk reduction. Ensures stem ejection is impossible when external non body/bonnet fasteners are removed.

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7.5.1.22 Ball and butterfly valves shall have an anti-static device.

Justification

Prevent electric static discharge which could cause a fire.

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7.5.1.23 When the service is air or water, carbon steel piping shall have a corrosion allowance of 1.5 mm (1⁄16 in.) or greater.

Justification

Prevents pipe leaks due to corrosion.

7.5.2 Oil Piping

Add new section

7.5.2.4 Tubing may be used for sizes DN 15 (NPS ½) and smaller.



Justification

Tubing has adequate provision for sizes 1/2" and smaller.

Add new section

7.5.2.5 Compression tube fittings shall be flareless, double-ferrule type.

Justification

Provides robustness and reliability of oil system tubing. Double ferrule provides tight sealing for pressures up to 6000 psig

Add new section

7.5.5 Pipe support

7.5.5.1 Piping shall withstand reaction forces from pressure relief and blow-off valves.

Justification

Reduces failure of pipework by designing for all known forces.

7.5.5.2 Vent, drain and small-bore connections DN 50 (NPS 2) and smaller shall have bracing.

Justification

Provides protection against vibration and accidental knocks from personnel.

Replace section 7.6 title with

7.6 Intercoolers, Aftercoolers and Other Pressure Equipment

7.6.2

Add to section

The drain valve shall be fitted at the lowest point of the cooler inclusive of moisture separator.

Justification

To provide complete drainage of the cooler.

Add to section

Electronically operated automatic drain traps with bypass shall be provided.

Justification

Reduces maintenance requirements.

Add to section

When drain traps use a solenoid, the solenoid shall be H-rated, with stainless steel body and soft seal.



Justification

Provides durability and reliability for drain traps.

7.6.4

Add to section

Water on the shell side of a sea-water cooled heat exchanger shall not be used.

Justification

Prevent fouling of heat exchanger shell side from trapped salt deposits. Shell side is more difficult to clean than tube side.

7.6.6

Add to section

Intercooler and aftercooler materials shall be in accordance with Table 2.

Justification

Provides common standard for material selection that has the minimum acceptable requirements.

Add to section

Air-cooled cooler materials shall be in accordance with Table 2.

Justification

Provides common standard for material selection that has the minimum acceptable requirements.

Add new section

7.6.9 Non-integral aftercooler, oil cooler, and fabricated pressure equipment shall be designed and constructed in accordance with the specified pressure design code.

Justification

Ensures pressure equipment compliance with an acceptable international design code.

Add new section

7.6.10 Integrated intercooler and aftercooler part of compressor casing or extended pressure casing shall be vendor's standard design and construction.

Justification

Permits a technically acceptable alternative vendor standard which may offer advantages over heavy duty process type coolers.




7.7 Inlet Air Filter and Silencer

Add new section

7.7.3 Inlet air filter and silencer materials shall be in accordance with Table 2.

Justification

The material selection meets minimum acceptable requirements.

Add new section

7.7.4 The piping between the inlet air filter or silencer and the compressor air inlet flange, shall be 316 stainless steel or carbon steel with non-metallic lining or insert.

Justification

The material selection meets minimum acceptable requirements.


7.9 Special Tools and Spare Parts

Add new section

7.9.3 Spare parts shall be the same as were supplied for the original component.

Justification

Ensures spares are a duplicate of the original equipment.

8 Inspection, Testing and Preparation for Shipment

8.3 Testing

8.3.3 Impeller Overspeed Test

8.3.3.3


On completion of the overspeed test, each impeller shall be examined by magnetic particle or liquid penetrant methods.

Justification

Required to check for cracks in impeller surface or deformations.

Add new section

8.3.3.4 Acceptance criteria for MT and PT inspection of the impeller shall be in accordance with API RP 687:2015, Table 1.8-1, Severity level A.



Justification

Established acceptance criteria for test.

8.3.4 Combined Mechanical and Performance Tests

8.3.4.1

Add to first sentence before "performance"

thermodynamic

Justification

Clarifies that thermodynamic as well as mechanical performance must be validated.

Add to section

The thermodynamic performance test shall be performed on at least one machine of multiple order of identical machines.

Justification

Save cost and reduce schedule as there is no need to test each machine.

8.3.4.2

Replace "Aerodynamic" with

Thermodynamic

Justification

Correction to API 672.

Add new section

8.3.4.11 Lube Oil Flushing Test

8.3.4.11.1 Lube oil flushing and cleanliness test shall be carried out using a 100 mesh stainless steel screen.

Justification

Provides common standard for flushing and cleanliness test.

8.3.4.11.2 The flushing test shall be performed at least 1 hour prior to the combined performance and mechanical run test.

Justification

Provides common acceptance standard for the flushing test.

8.3.4.11.3 The flushing test fluid shall have a contamination level of ISO 4406 Grade 17/14/12 or SAE AS4059 Class 8.



Justification

Standardize on flushing test contamination level.

Add new section

8.3.4.12 Noise Test

8.3.4.12.1 Noise tests shall be conducted in accordance with ISO 2151.

Justification

Provides a common standard for noise tests of air compressors.

8.3.4.12.2 For multiple identical compressor packages noise testing shall be carried out on at least one compressor package.

Justification

Cost and schedule reduction by removing unnecessary testing.

8.3.4.12.3 Sound intensity scanning method shall be in accordance with ISO 9614-2.

Justification

Standardize on sound level test method.

8.3.4.12.4 Sound intensity system shall be in accordance with IEC 61043 Class 1.

Justification

Standardize on sound intensity system.

8.4 Preparation for Shipment

Add new section

8.4.14 Visible display units and control panel front face shall be protected against visible scratches during transportation and handling.

Justification

To protect against damage during transportation and handling.

Add new section

8.4.15 Provision for turning on the anti-condensation heater for motors while they are idle shall be stated in the preservation procedure.

Justification

Ensures adequate preservation is performed to prevent motor damage during transportation and storage.

Add new section

8.4.16 Open piping connections shall be blanked with material of compatible metallurgy.



Justification

Ensures adequate packing and preservation is performed to prevent piping and valve damage during transportation and storage.

Add new section

8.4.17 The outboard connection of valves open to the atmosphere shall be plugged or blinded.

Justification

Ensures adequate packing and preservation is performed to prevent piping and valve damage during transportation and storage.

Add new section

8.4.18 Preservation checklists and a preservation report detailing all preservation activities performed shall be completed.

Justification

Ensures adequate preservation is performed to prevent equipment damage during transportation and storage.



Bibliography

Add to section

[12] ISO 10418, Petroleum and natural gas industries — Offshore production installations — Process safety systems

[13] ISO 13880, Petroleum and natural gas industries — Content and drafting of a technical specification

[14] ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories

Supplementary Specification to API Standard 672 Packaged ...

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