MP12P02

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MP 12-P-02 Oil and Gas Separators July 1998

ExxonMobil Oil, 1997 2 of 11

Table of Contents

Scope...................................................................................................................................................1

1. References..................................................................................................................................3

1.1. Master PracticesExxonMobil Engineering Practices ..............................................3

1.2. ExxonMobil Data Sheets ...............................................................................................3

1.3. ExxonMobil Practice Tutorials ......................................................................................3

1.4. APIAmerican Petroleum Institute ...............................................................................3

1.5. ASMEAmerican Society of Mechanical Engineers .................................................3

2. General ........................................................................................................................................4

3. Design..........................................................................................................................................4

3.1. General.............................................................................................................................4

3.2. Sizing ................................................................................................................................5

3.3. Design Pressure ..............................................................................................................5

3.4. Separation Phases .........................................................................................................6

3.5. Nozzles .............................................................................................................................7

3.6. Internals ............................................................................................................................8

3.7. Minimum Dimensions for Vertical Separators............................................................9

3.8. Instrumentation................................................................................................................9

4. Piping.........................................................................................................................................10

5. Painting and Coatings...........................................................................................................10

6. Insulation ..................................................................................................................................10

7. Inspection, Testing and Documentation ..........................................................................11

8. Identification ............................................................................................................................11

Table of ContentsMEPS IndexPrev PageNext Page

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1. ReferencesThe following publications form a part of this Practice. Unless otherwise specified herein, use thelatest edition.

1.1. Master PracticesExxonMobil Engineering Practices

MP 12-P-01 Pressure Vessels-Design & Fabrication

1.2. ExxonMobil Data Sheets

ExxonMobil DataSheets

ExxonMobil Data Sheet Home Page

T1202C01 Oil and Gas Separators - Customary Units

T1202M01 Oil and Gas Separators - Metric Units

1.3. ExxonMobil Practice Tutorials

EPT 03-T-05 Two Phase Separators

EPT 04-T-13 Fuel Gas Systems

1.4. APIAmerican Petroleum Institute

API SPEC 12J Specification for Oil and Gas Separators Seventh Edition

1.5. ASMEAmerican Society of Mechanical Engineers

ASME B31.3 Process Piping

ASME SEC VIIIDIVISION 1

BPVC SECTION VIII Rules for Construction of Pressure VesselsDIVISION 1 Non-Interfiled (Boiler and Pressure Vessel Codes)


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2. GeneralThe design and selection of oil and gas separators, including liquid knockouts, traps, flash vessels andscrubbers, for general use in onshore and offshore production and processing facilities, shall conform

to the requirements of the project specifications and shall be in accordance with requirements of thisEMEP, unless superceded by more stringent local regulations.

The process design of suitable pressure vessels for this service requires data on the gas,

oil/condensate and water produced, as furnished on the ExxonMobil Data Sheetsfor this MasterPractice The process design also requires knowledge of separation of gas, oil/condensate and water.

The vendor of this equipment shall have the knowledge and the experience to design and fabricatesuitable separators for the desired service.

1. Process design criteria and any specific internal details are shown on the ExxonMobil Data Sheetsfor this Master Practice.

2. Mechanical design, specific nozzle orientation, materials, fabrication and inspection and testingof the separator shall be in accordance with MP 12-P-01.

3. All vessels for U.S. and Canadian locations shall be ASME code stamped and registered with theNational Board of Boilers and Pressure Vessel Inspectors. For locations where codes other thanASME apply, a separate, supplementary specification demonstrating compliance with local

and/or statutory requirements is required.

4. Any piping components included with the separator that are outside the jurisdiction of ASME

SEC VIII DIVISION 1shall be designed and fabricated in accordance with ASME B31.3.5. The corrosion allowance shall be in accordance with the project specifications.

This Practice does not cover centrifugal separators, filter separators, coalescing separators or de-sanding separators. This Practice also does not cover the requirements for a packaged unit. Should a

packaged separator be required, refer to the appropriate EMEPS for packaged units, instruments,

electrical, painting and insulation as required.

3. Design

3.1. General

The technical requirement for oil and gas separators shall be based on API SPEC 12J.

The following requirements are in addition to those specified in API SPEC 12J.


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3.1.1. Minimum Provisions

The separator design shall provide or make provisions for the following, as a

minimum:

1. A primary separation section, to make the initial separation of liquidfrom the gas, using deflection

2. A secondary separation section to allow liquid particles to fall toward theliquid accumulation section under gravity

3. A liquid accumulation section that provides liquid retention time for bothliquid/liquid separation and break-out of gas in solution

4. A mist extraction section to remove entrained droplets

5. Sufficient liquid capacity to handle surges of liquid

6. Sufficient gas flow length and height above maximum operating liquidlevel, to allow small droplets to settle out by gravity, preventing

excessive entrainment

7. A means of reducing turbulence in the main body of the separator so thatproper settling may take place

8. Process controls for pressure and liquid levels

9. Over-pressure relief for the vessel

3.1.2. Vertical or Horizontal Vessels The separator design may use either vertical or horizontal vessels.

Spherical vessels are not to be used unless specifically approved byExxonMobil. Unless specified on the ExxonMobil Data Sheetsfor thisMaster Practice, the vendor's choice of vertical or horizontal vessels shall

be based on process requirements and constraints of installation, locationand economics. This selection shall be approved by The Company prior

to proceeding with the design.

3.2. Sizing

The separator shall be properly sized by the vendor, using proven sizing techniques for the

operating conditions as stated on the ExxonMobil Data Sheetsfor this Master Practice.Both minimum and maximum operating conditions shall be considered in the sizing.

ExxonMobil shall approve all proposed sizing techniques by the vendor prior to design.

3.3. Design Pressure

This EMEP defines pressure terminology as follows:


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Normal Operating Pressure: the operating pressure in the vessel for normalcontinuous operation

Maximum Operating Pressure: the maximum expected operating pressure forcontinuous operation without causing shutdowns or relieving conditions

Maximum Allowable Working Pressure (MAWP): the maximum pressurepermissible by the ASME Code for a designated temperature

3.3.1. Maximum Allowable Working Pressure (MAWP)

The maximum allowable working pressure (MAWP) of a separator shall besufficiently above the maximum operating pressure, and also above the

pressure settings of high-pressure alarms and shutdown devices, to preventinadvertent lifting or leaking of safety relief valves.

Where desired for flexibility and/or when economically feasible, MAWPsshall be based on Tables 4.1 and 4.2 in API SPEC 12Jor maximum flangeratings in accordance with ASME SEC VIII DIVISION 1. ExxonMobil

operations generally use MAWPs of 125 psig, 720 psig, 1440 psig or 2160psig to optimize flexibility for reuse of vessels or operating pressure changes.

Where these pressure ratings are not economical, the design pressure for thevessel shall be as determined in the Appendix of MP 12-P-01.

3.4. Separation Phases

The selection of two-phase or three-phase separation shall be consistent with overall

process requirements where the separator is to be installed.

Most scrubber vessels and production separators use two-phase separation and requirefurther downstream processing of the liquid for oil/water separation.

If multi-stage separation is desired, two-phase separators may be used on all but onestage of separation, with the last stage being a three-phase separator.

Test separators shall be of three-phase design unless otherwise approved by TheCompany.

3.4.1. Two-Phase Separators

For two-phase separators, the liquid retention time for gas separation from

liquid shall be determined by using criteria presented on the ExxonMobilData Sheetsfor this Master Practice, but shall not be less than one minute.

Sizing of fuel gas mix drum and fuel gas knockout pots shall be inaccordance with EPT 04-T-13.


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3.4.2. Three-Phase Separators

For three-phase separators, the liquid retention time for oil/water separation

shall be determined by using criteria presented on the ExxonMobil DataSheetsfor this Master Practice, but shall not be less than three minutes.

3.5. Nozzles

Separators shall have the following nozzles as a minimum:

1. Inlet

2. Gas outlet

3. Liquid outlet (two outlets if three-phase separation is desired)

4. Relief valve

5. Drain (minimum of one per vessel section)

6. Liquid level control

7. Liquid level indication connection(s)

8. Thermowell connection

9. Pressure gauge connection

10.Inspection openings or manway with davit

11.High-level shutdown

12.Low-level shutdown

13.High- and low-pressure shutdown

3.5.1. Nozzle Orientations and Location

Nozzle orientations and locations shall be located to best facilitate piping andinstrumentation, maintenance and plant operations.

3.5.1.1. Process Nozzles

Process nozzle sizes shall be determined by the line sizes necessary to handlethe required liquid and gas flow rates. Nozzles shall generally be the same

size as, or larger than, the piping to and from the separator. Nozzle sizessmaller than the piping shall be reviewed and approved by The Company

prior to final design.


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3.5.1.2. Nozzles for Liquid Level Controls and LevelIndicators

Nozzles for liquid level controls and level indicators shall be located tofacilitate viewing the level while calibrating and setting the level controller.

3.5.1.3. Nozzles for Relief Valves

Nozzles for relief valves shall be sized to accommodate a relief valvethat will handle the maximum inlet volume anticipated to the separator atthe maximum allowable working pressure of the separator.

Nozzles for the relief valve shall originate upstream of the mist extractorand be located well above the maximum liquid level.

3.5.1.4. Nozzles for External-Mounted Devices andLevel Sight Gauges

Nozzles for external-mounted level devices and level sight gauges shall be

jig-set during fabrication.

3.6. Internals

3.6.1. Inlet Deflector or Distributor

The separator shall be equipped with an inlet deflector or distributor designedto promote separation and prevent erosion of the vessel's pressure containing

components. In vertical vessels, the inlet deflector design shall preventupward flow of the inlet stream. More sophisticated devices, such as dished

deflectors and centrifugal deflectors, may be used.

3.6.2. Mist Extractor

The separator shall be equipped with a mist extractor upstream of the gas

outlet.

As a minimum, the mist extractor sha ll be constructed of 316 stainlesssteel wire mesh with a density of 150 kg/m3 (9 lb/ft3) and shall be 150

mm (6 in) thick.

In vertical vessels, the mist extractor shall span the full cross-section ofthe vessel.

In horizontal vessels, the mist extractor shall be mounted vertically andspan the entire vessel cross-section that is exposed to gas flow.

The mist extractor design shall provide for removal through the manway.


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3.6.3. Vortex Breakers

All vessel liquid outlets shall be equipped with vortex breakers. Vortex

breakers shall be designed not to restrict the flow capacity of the liquidoutlets.

3.6.4. Baffles

Vessel design shall include necessary internal baffles and other devices, such

as downcomers, oil buckets, etc. to achieve the required degree of separation.Provisions shall be made in baffles to allow access throughout the vessel.When internal baffles are used, pressure-equalizing pipes shall be employedas needed.

3.6.4.1. Matrix-Pack Type Sections

Matrix-pack type sections may be installed to aid liquid/liquid separationwhere an additional coalescing medium is needed. Distribution baffles are

typically used in conjunction with these packed sections.

3.6.5. Internal Float Controls

Internal float controls, where used, shall have shields to prevent upsets due toturbulence.

3.6.6. Sand Flushing and Dumping

Where sand production is anticipated, vessel design shall make provisions forsand flushing and dumping.

3.7. Minimum Dimensions for Vertical Separators

In vertical separators, the distance between the inlet nozzle centerline and the bottomof the mist elimination pad shall be equal to the diameter of the vessel, but not lessthan 1 m (3 ft).

In vertical separators, the distance between the inlet nozzle and maximum liquid levelshall be one-half the vessel diameter, but not less than 0.6 m (2 ft).

In vertical separators, the liquid accumulation area shall occupy a minimum of 0.5 m(1.5 ft) of the shell vertical height.

3.8. Instrumentation

All instrumentation devices specified or supplied by the vendor shall require approval byThe Company and meet project specifications.


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3.8.1. Liquid Level Control

Vessel design and nozzle locations shall make provisions for the type of

liquid level control specified on the ExxonMobil Data Sheetsfor this MasterPractice.

Liquid level control can be handled in several ways, including:

Internal float operation (horizontal or vertical)

Internal capacitance probes

Internal sonic probes

External displacer/float (bridle)

Differential pressure transducer

3.8.1.1. Liquid Level Indicators

In sizing and locating vessel connections for liquid level indicators, the typeof indicators shall be taken into account.

All instrument tubing shall be stainless steel.

4. Piping

All piping, valves and fittings specified or supplied by the vendor shall be approved by The Company

and meet project specifications.

5. Painting and Coatings

Process requirements for internal coatings are as specified on the ExxonMobil Data Sheetsfor thisMaster Practice. All coating systems proposed by the vendor shall be approved by The Company and

meet project specifications.

6. Insulation

Process requirements for insulation are as specified on the ExxonMobil Data Sheetsfor this MasterPractice. All insulation systems proposed by the vendor shall be approved by The Company and meet

project specifications.


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7. Inspection, Testing and DocumentationInspection, testing and documentation shall be as specified in MP 12-P-01.

8. Identification

The vessel shall be marked per MP 12-P-01. If the vessel is to be insulated, the nameplate bracketshall be designed to extend through the insulation.

MP12P02

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