S U M M E R 2 0 0 2

SPOTLIGHT ON OIL & GAS

PAGE 4CONTROL’S A GAS WITH CCI

PAGE 2-4BAD VIBES REPLACED WITH SEVERE SERVICE DESIGN

PAGE 7CCI HELPS WILPRO GO FULL THROTTLE

PAGE 7TECHNOLOGY IS A DRAG® AT DAKOTA

PAGE 8DRAG® HELPS KEEP THUNDER HORSE UNDER CONTROL

PAGE 6NOISE TAKES ON GULLFAKS C TURNS FOR THE BETTER WITH DRAG®

PAGE 5THE PRESSURE’S OFF AT SECUNDA

2

HOW DRAG®

ELIMINATES

HIGH VIBRATION LEVELS

Bad Vibes Felt at Offshore Platform— Replaced with DRAG® Design

EVER SINCE INITIAL OPERATION IN MID-1998, the 8-in.

(200-mm) recycle valves in the main oil line (MOL) export

system Eastern Trough Area Project offshore platform had been

experiencing extreme vibration problems. This North Sea platform is

operated by BP AMOCO on behalf of its partners.

Flow-induced vibration was extreme in the valves themselves, causing

excessive vibration as well as of the associated piping and structures.

The valves were suffering from continual failures in the gland-packing

assemblies, instrument and air supply tubing, and the mechanical and

electronic components of the position feedback control assemblies.

These MOL export pump recirculation valves were designed for a

maximum flow of 900,000 lb/hr (404,000 kg/hr) at inlet pressures

as high as 3200 psia (220 BarA) and ΔPs of 2900 psi (200 Bar) at

150 F (63 C).

After an evaluation of the problem in July of 1999 by JMDynamics,

it was recommended that the valves be replaced. However, for

operational reasons, this could not be immediately done. A revised-

design trim replacement in these three-stage cage/diffuser valves was

accomplished, but this failed to mitigate the severity of the vibration

problem.

On May of 2001, JMDynamics was called in to again evaluate this

continuing vibration problem. The company used Southwest Research

Institute’s (SRI) vibration-

level criteria as a guide

only for the evaluation

of results from piping

vibration testing. These

provide vibration criteria

acceptance as a function

of frequency and use two

predominant levels of

acceptance.

Figure 1: The replacement “A” MOL recycle valve

3

When these MOL

pumps startup

or shutdown,

the control

valves are 100-

percent open. From

a vibration point of view, this is

their most critical operating condition,

and a maximum vibration level of 25 mm/sec RMS

was recorded in the horizontal direction on the control-assembly

mounting plate; the dominant frequency was 29 Hz.

At this point, JMDynamics’ original recommendation that

these valves be replaced with new CCI severe service valves was

instigated. These valves are specifically designed to minimize

vibration through limiting trim flow velocity for this severe, very

high ΔP service.

Replacement Valve Design

To eliminate the destructive effects and potential dangers of

high vibration levels in the severe-service application, the new

replacement valves (Figure 1) are designed to limit trim fluid

velocities to less than 100 ft/sec.

This is accomplished through multi-stage pressure reduction

(over 20 stages) within a stack of tortuous-path, electro-

discharge-machined (EDM) disks containing a series of

sequential, right-angle turns, Figure 2. In addition, each disk

incorporates a pressure-equalizing ring (PER) on its inside

diameter to ensure that equal pressure acts radially around the

circumference of the plug at any position in its stroke. This

design keeps the plug centered at all loads, thus preventing plug

vibration that could cause galling and impede free stroking

motion.

Also, the actuator control is provided with a snap-action relay

which is set to reduce operating time of the valve at very low

Table 1: A 1999 vs. 2001 comparison of the RMS vibration measurements on valve actuators and bodies taken in XYZ directions.

Description LocationJuly 1999 Results* October 2001 Results*

Valve A Valve A Test 1 Test 2

100% Open 30% Open A-100%, B-60% B-100%, A-10%

Valve Actuator

1x 24.7 4.5 2 2.1

y 17.4 8.4 3.1 4.0

z - - 1.2 1.6

Valve A Body

4x 8.6 1.4 0.7 0.6

y 10.3 1.4 1.4 1.4

z 18.6 - 1.3 1

Valve B Actuator

11x 12.5 - 2.9 2.6

y 16.1 - 4.4 3.8

z - - 1.2 1

Valve B Body

14x 6.8 - 0.9 0.8

y 8.0 - 0.9 1

z - - 0.8 0.7

* Pump and valve A operating only, no flow through pump or valve B

Figure 2 – A multi-stage pressure reduction

disk stack with individual disks showing the

right-angle, tortuous flow paths.

Figure 3: A schematic of the two, parallel MOL pump recycle

systems showing the points of valve vibration measurement.

(Continued on page 4)

Control’s a Gas with CCI

4

flows when the plug would be close to the seat. Under the

close seat/plug conditions, high, resultant fluid velocities

could result over time in seating surface erosion.

Results of Valve Replacements

Vibration levels were recorded not only at many points

throughout the MOL recycle valve associated piping and

support structures, but of course also on the two valve bodies

and actuators involved as indicated in Figure 3. Table 1

shows comparatively the root-mean-square (RMS), vibration

reduction by a factor of 10 at these valve locations between

the original valves tested in 1999 and the multi-stage

pressure reduction valves tested in October of 2001. Figure

4 shows a typical peak actuator vibration comparison under

Figure 4: A typical plot of before and after actuator peak vibration

spectra over a wide frequency range.

(Continued from page 3)

relatively comparable conditions. This vibration level reduction is

even more significant since the replacement valves operate at a higher

flow and pressure drop than the original valve. In addition, there is

now virtually no transmission of vibration energy to the piping and

support structure.

CONTROL VALVES IN THE GAS

TRANSMISSION INDUSTRY have

traditionally sacrificed capacity and noise

for low-end control. For many systems,

flow-impinging valves may seem the best

solution, but they don’t offer both high

capacity and low-end control in optimal

ranges. This results in gas transmission

organizations having to accept the

need for expensive bypass systems and

the willingness to live with noise and

cavitation.

To address these needs, CCI has introduced

the Rotary DRAG® valve which marries

the high capacity of a rotary valve and the

proven multi-stage technology of DRAG®.

With the potential for more than 28

stages of pressure reduction, the result is

an axial flow control valve with very high

capacity, and low-end control that rivals

all other valves on the market. Now the

applications that traditionally utilized two

valves in parallel will only need one Rotary

DRAG® valve. This creates a substantial overall reduction in maintenance costs and

eliminates the need for low-end bypass control for most gas transmission applications.

At a minimum, Rotary DRAG® technology will impact future design considerations for

gas interconnect, distribution and blending stations, as well as the basic design and

control philosophies used within the transmission industry.

The valve industry realizes that designs

utilizing expanding right-angle

flow paths effectively reduce

fluid velocities and provide

effective valve control.

The cost of this

control has always

been capacity;

however, with the

introduction of

the CCI Rotary

DRAG® valve, gas

transmission

groups will no

longer need

to make the

decision between

valve capacity and

performance.

5

SASOL RECENTLY FACED A CHALLENGE WHEN ONE OF

THE VALVES INSTALLED AT ITS SECUNDA PLANT BEGAN

EXPERIENCING PROBLEMS. The plug on one of the existing valves

kept separating; this caused rotating and damaging of the plug, the

seal ring, and jamming of the valve. The pin holding the stem also

came loose, requiring an efficient replacement at Secunda.

Understanding why a selected valve is not performing satisfactorily

is not always known and in many cases is accepted as the norm.

Many attempts throughout the industry aim to resolve the

problems by addressing the effects of the damage. For example, the

use of harder materials when erosion and cavitation damage occur.

These solutions only marginally prolong the time at which failure

will take place. Problems like erratic control, noise, mechanical

vibration, cavitation, erosion, and short life are best solved by

controlling the cause of damage.

To overcome Secunda’s challenges, CCI provided a resolution that

would address the root cause of the problem with a customized

specification for the site’s steam pressure application. Sasol

received two, 16-in. x 16-in. (400-mm x 400-mm) control valves

The Pressure’s Off at SecundaThe DRAG® disk

stack incorporates a

pressure equalizing

ring on its inside

diameter to ensure

equal pressure

acting radially on

the valve plug at all

times. This eliminates

the vibration that could

occur because of rapid plug

radial movement.

with design temperatures of 570 F (300 C). Incorporating

DRAG® technology, the disk stacks have pressure equalizing

ring (PER) grooves built into them and each disk is made with

a land on the inside diameter so that localized pressure from

each disk’s outlet is equalized around the plug. This eliminates

radial forces on the plug which might otherwise cause binding

in under-the-plug applications and/or radial vibration and

buffeting in over-the-plug applications.

THE CHALLENGE OF THE RICH-AMINE APPLICATION IS

A COMPLEX ONE; the process begins when amine liquid is

pumped into the top of a column and raw gas enters along the

bottom, passing through the amine liquid as it rises. This process

removes H2S and CO2 from the gas and absorbs it into the amine

liquid, allowing the gas to leave the column “clean” and ready

for distribution or use in a refinery. The remaining amine at the

bottom of the column is now referred to as “rich amine.”

The column is maintained under pressure to improve the

efficiency of the absorption process. At this pressure and

saturation point, the rich amine is a multi-constituent fluid with

a vapor pressure close to that in the column. As the fluid passes

through the rich amine letdown valve, the pressure drops across it,

causing the gases to be released from the amine.

If a valve’s design is based on a

presumed lower vapor pressure,

catastrophic consequences can

result, such as high mechanical

vibration that shuts down

the train. DRAG® technology

provides the number of pressure-

reducing stages required to limit

the kinetic energy produced,

providing the needed reliability

to keep production running and

producing profit.

Rich-Amine Letdown in Refineries and Gas Processing Plants

WHEN STATOIL’S GULLFAKS C PLATFORM RECENTLY

UPRATED ITS COMPRESSORS, they revamped their

piping and replaced their compressor-recycle valves. During

initial testing on Train A in early October 2001, they observed

excessive noise levels – as high as 126 dBA – within the

revamped piping surrounding a new recycle valve and the valve

itself, Figure 1.

The piping revamp included five new elbows and two flange

joints within 15-ft (4.5-m) of the valve inlet. It also included

an 18.5-in. (455-mm) spool piece to reduce the pressure class

just downstream of the valve. This was accommodated by a

spool piece that included one 1500 ANSI flange joint, one 600

ANSI flange joint and a slight expansion in the spool itself to

accommodate the decrease in pipe wall thickness, Figure 2. The

flanged joints were all the ring-type joint (RTJ) design.

Because the high frequency noise was judged to be in excess

of 85 dBA, and the noise seemed to have a “trigger” point

associated with a specific valve lift, CCI was contacted by Statoil

and Aker Engineering to assist in determining the source of

the noise. An audit confirmed that the valve should not be

producing the noise, and that there was no noticeable vibration

of the valve stem or actuator, something frequently related to

noise.

Statoil and Aker Engineering contracted a consulting firm to

learn about the specifics of the observed noise. They carried

out detailed and accurate noise measurements under varying

compressor and valve operating conditions. The dominant

noise frequency was 2000 Hz and the peak noise level was

126 dBA. This peak noise level occurred at the ANSI 1500/600

transitional spool piece. The noise level in the upstream piping

ranged from 112 to 115 dBA. Farther downstream, where the

piping was insulated, the noise level dropped off from 123 dBA

to 113 dBA.

It was decided that a spare valve made at the same time as the

one at Train A would be disassembled and inspected while the

installed valve continued to be used for compressor testing. It

was also decided that at the next shutdown, a flexible perfluoro-

elastomer filler material would be installed into the RTJ flange

gaps at the inlet and outlet end of the spool piece to assess

its impact on reducing the noise at that location. At that time,

the installed valve could also be visually inspected through

the valve outlet to see if any constructional anomaly could be

observed. After this

modification was

completed, and

upon restarts of the

Train A compressor,

a significant noise

reduction was

observed (in excess

of 10 dBA) such that

the dominant noise

now seemed to be coming from the upstream side of the valve. The

dominant frequency remained at about 2000 Hz.

Based on this experience, it was concluded that the source of the

noise was probably not the valve, but rather the piping, and it

was further decided to install soft fill-in gaskets in the RTJ flanges

upstream of the recycle valve as well. This was carried out a few days

later during a scheduled compressor stop. New noise measurements

were again taken that showed the previous high-frequency noise

in the piping system adjacent to the anti-surge valve had been

eliminated.

The final conclusion was that the noise arose solely from significantly

increased gas velocity in the piping following the uprated capacity

of the export compressor. When the gas velocity in the piping, as

determined by the valve opening position, became sufficient, it

triggered a resonant frequency in the flange gaps (similar to blowing

across the top of an empty bottle).

Checking conventional design rules for gas service pipe sizing also

showed that the

compressor uprating

had produced

a significantly

increased gas

velocity over normal

recommendations

for the pipe sizes

involved. It was

further concluded

that the anti-surge

recycle valves did

not represent any

significant noise

problem in Satoil’s

current operations.

Noise on Gullfaks C Takes a Turn for the Better with DRAG®

Figure 1

Figure 2

6

7

AT THE DAKOTA GASIFICATION

COMPANY, AN EXISTING VALVE was

experiencing erosion of the trim. This resulted

in high maintenance for the company, and

required a solution to handle the process

conditions of the Dakota Gasification

Company.

Typical problems caused by incorrect

technology in severe service valves include

premature trim and body erosion due to lack

of velocity control along the flow path. Trim

damage reduces the trim’s ability to control

spraywater flow, which is why it’s important

to avoid high velocity areas. Avoiding this

occurrence allows for the life of the trim to

increase considerably. CCI’s unique DRAG® design produces a highly

reliable and precise level of flow control to

eliminate the possibility of erosion problems.

To address this issue, Dakota Gasification

is replacing the valve with a 1-in. (25-mm)

globe valve, specifically designed to handle

Dakota’s application requirements. By

utilizing DRAG® technology, the risk of

uncontrolled fluid velocity is eliminated

through the unique tortuous path trim

design. This controls fluid velocity by

forcing the pressure drop to occur in

several stages, reducing it as it passes

through each channel and stage. The

replacement valve will have design

pressures of up to 1500 psig (103 bar) with

temperatures up to 300 F (150 C).

Technology is a DRAG® at Dakota

CCI Helps Wilpro Go Full Throttle

AT WILPRO’S EL FURRIAL SITE

IN VENEZUELA, gas to flare

valves were creating problems in

production. These existing valves

were suffering from gas leakage when

closed, and high noise levels during

venting conditions that Wilpro found

unacceptable.

Leakage in the gas to flare application

creates serious issues for a plant,

particularly since the products that

need to be flared tend to be high cost

items. A constantly leaking valve also

causes energy from the system to be

lost, which increases plant costs. Even

a minute leak can grow quickly into

a large one, eventually affecting the

valve’s internal parts performance.

Additionally, El Furrial was also

experiencing high noise levels during

venting, which in gas to flare can

indicate a high-pressure drop that

results in shortened life and high

maintenance costs.

For these reasons, El Furrial is

replacing its valves with two, 14-in.

(355-mm) 100D DRAG® valves. With

design pressures up to 1350 psig (93

bar) at temperatures that range up to

120 F (50 C), these replacements will

eliminate the possibility of excessive

noise by using unique multi-passage

trim designed to control high pressure

drop. In addition to this, the DRAG®

valves are specifically designed for

long-term shutoff, to avoid any

unnecessary seat leakage. A DRAG® block angle valve similar in design to the

one supplied to El Furrial.

8

CCI World HeadquartersTelephone: (949) 858-1877Fax: (949) 858-187822591 Avenida EmpresaRancho Santa Margarita,California 92688 USA

CCI Switzerland Telephone: 41 52 262 11 66Fax: 41 52 262 01 65Hegifeldstrasse 10CH-8404 WinterthurSwitzerland

CCI Sweden (BTG Valves)Telephone: 46 533 689 600Fax: 46 533 689 601Box 603SE-661 29 SäffleSweden

CCI ChinaTelephone: 6501 0350 0650Fax: 6501 0286Room 567/569 Office TowerPoly Plaza14 Dongzhimen South AvenueBeijing 100027China

CCI KoreaTelephone: 82 341 980 9800Fax: 82 341 985 055226-17, Pungmu-DongGimpo CityKyunggi-Do 415-070Republic of Korea

CCI Austria (Formerly Spectres Components GmbH)Telephone: 43 1 869 27 40Fax: 43 1 865 36 03Carlbergergasse 38/Pf. 19AT-1233 ViennaAustria

CCI ItalyTelephone: 39 035 29289Fax: 39 035 2928246 Via G. Pascoli 10A-B24020 Gorle, BergamoItaly

CCI JapanTelephone: 81 726 41 7197Fax: 81 726 41 7198194-2, ShukunoshoIbaraki-City, Osaka 567-0051Japan

Contact us at:info@ccivalve.com

All rights reserved. Solutions™, DRAG® and CCI DRAG® are trademarks of CCI. CCI valves are manufactured under various United States and international patents.

©2002 CCI 518 8/02 10K

Visit us online at:www.ccivalve.com

DRAG® Helps Keep Thunder Horse Under Control

BP AMOCO DISCOVERED FOUR OIL FIELDS IN

THE GULF OF MEXICO, known as Atlantis, Mad Dog,

Holstein and Thunder Horse. Of these Thunder Horse

is the largest, located 6,000 ft (1830 m) in the Boarshead Basin.

With estimated recoverable oil of at least one billion barrels of

oil equivalent (boe), it is the biggest discovery ever made in the

Gulf deepwater.

To ensure that all equipment used in this project will have the

utmost reliability, BP Amoco chose DRAG® valves for their water

injection pump recycle application. These four, 4-in. (100-mm)

100D angle valves have been designed for inlet pressures of up to

8600 psig (593 bar), with temperatures up to 200 F (93 C).

Challenging the project is the need for absolute reliability:

because most deepwater projects are justified by their huge

energy reserves, any loss of revenue as a result of unexpected

shutdown can easily exceed the high remediation cost.

Experience shows that fluid velocity control along the flow path,

as in DRAG® technology, is necessary for long-term reliable

performance. By combining CCI’s unique capability to easily

vary the number of disks in each stack, a DRAG® valve eliminates

problems such as trim and body erosion, noise vibration and

poor process control that can result from excessive fluid velocities.

This is why it is essential that the valve design features match the

specific application requirements. If this is not so, then there is

little hope that corrective actions after installation will be able to

overcome the initial errors.

DRAG® technology will be supplied to Thunder Horse, one of the

largest oil discoveries made to date by any company.