Misconceptions and Misapplication of Production Valve Test Standards It’s really about detecting Leaks

Greg Smith- Director, Quality and Productivity

Improvement

From an engineering viewpoint there is no such thing as a “zero leak”

Std cc/sec Reference Rate Comments

1x10-8 Leak 1 cc every 3 years Diffusion of helium through

glass per square cm of

surface area

1x10-7 Leak rate of 3 cc/year About the size of 3 marbles

1x10-6 About 1 cc every 2 days Breathing on a leak this size

can provide enough

moisture to temporarily close

the leak

1x10-5 About 1 cc/day Better deploy a wetting

agent to detect this during

water immersion testing

1x10-4 About a cc every 3 hours Visible bubbles rising in

water immersion

1x10-3 4 cc/hour A leak of this size is readily

detectible using water

immersion

1x10-1 & up Too much! Audible

Definition of Leak Testing Sensitivity

Leak test sensitivity refers to how small a physical leak

can be detected, that is the minimum detectable size of

leak.

To avoid the difficulty of using dimensions that usually

could never be measure, a leak is measured by how

much leakage will occur in a specific period of time

under specific leak test conditions.

(ASNT NDT Handbook 2nd Edition)

Many of the Industry Specifications define the Test

Conditions , and in that sense they become

standardized.

Example from API 598

Gas test at 41 deg F -122 deg F

Pressure differential for the test 60-80 psig

Test Media Air or inert gas

:

Variations in basic test parameters

:

Standard Gas Test water

chlorides

Temperature

ASME B16.34 > 80 psi NA <125 deg F

API-598 60-80 psi <100* 41-122 deg F

MSS SP-61 60-100 psi NA <125 deg F

ISO-5208 6 bar +/-1

bar(73-102

psi)

<100* >5 deg C < 40

deg C(41-106

deg F)

API 6D NA <30**

(by mass)

>5 deg C < 40

deg C(41-106

deg F)

*austenitic stainless steel valves

** wetted components austenitic & duplex stainless steels

Visual Acuity for Test Operators

Check the vision of testing personnel

annually for their natural or corrected near

distance acuity. SNT-TC-1A recommends

"Jaeger Number 2 or equivalent type and

size letter at the distance designated on the

chart but not less than 12 inches (30.5 cm)

on a standard Jaeger test.

(From a practical perspective, a color blind

test is encouraged as well)

Test Configuration…continuedProvide a clear and unobstructed view of the test

valve

•Direct visual examination may usually be

made when access is sufficient to place the

eye within 24 in. (600 mm) of the surface to

be examined and at an angle not less than

30 deg to the surface to be examined.

•The minimum light intensity at the

examination surface/site shall be 100

footcandles.

Test Configuration

When a view of the test object is obstructed:

Remote visual examination may have to be

substituted for direct examination. (Mirrors,

telescopes, borescopes, fiber optics,

cameras, or other suitable instruments shall

have a resolution capability at least

equivalent to that obtainable by direct visual

observation.

Para-phased from 2007 ASME V

Sensitivities Attainable with Immersion Bubble TestingThe sensitivity of the bubble emission leak test is hard

to define because this depends upon the observation

and alertness of the leak test operator

When locating leaks in the 10-4 std. cm3/sec. the

component after being immersed, has to be completely

stripped of attached air bubbles so that the bubbles

formed by leakage gas may be detected.

It is an ideal method for quick detection of large to

moderate size leaks (10-2 std.cm3/sec. to 10-3 std.

cm/sec)at very low costs

(ASNT NDT Handbook 2nd Edition)

Sensitivities Attainable with Liquid Film Bubble Testing

The sensitivity of the liquid application technique of

bubble leak testing is adequate for locating leaks with

leakage rates in excess of 10-4 std. cm3/sec.

(pg.393 ASNT NDT Handbook 2nd Ed.)

The bubble forming solution shall produce a film that

does not break away from the area to be tested, and

the bubbles formed shall not break rapidly due to air

drying or low surface tension. Household soap or

detergents are not permitted as substitutes for bubble

testing solutions.

The bubble forming solution shall be applied to the

surface to be tested by flowing, spraying, or brushing

the solution over the examination area.

2007 ASME V

Improve the Sensitivity of Bubble Testing

Increase the pressure differential across the leak

Apply a gas with a low molecular weight

Introduce gas prior to immersion in detection liquid.

Optimize the position of test surfaces intended for

visual observation

Improve the lighting to highlight bubble emissions

Use clear translucent immersion fluids & maintain

clarity

Increase time for bubble formation & observation

Eliminate any false bubble indications

Decrease the surface tension of the detection liquid

so formed bubbles are smaller

Personnel Safety and Testing with Compressible Fluids:

Shock wave overpressures:

A pressure wave of >5 PSI eardrum rupture

>15 PSI permanent lung

damage

>35 PSI fatalities

(ASNT NDT Handbook 2nd Ed.)

When inert gas is used, safety aspects of

oxygen deficient atmosphere should be

considered.

Mitigation of Risk

Shell tests are specified to accomplish the following:

“A pressure test in excess of the cold-working

–pressure , CWP, rating of the valve for the purpose of

validating the soundness and strength of the valve

pressure containing structures.”

API598 ninth edition

“Test at a pressure in excess of the cold

working pressure rating of a valve for the purpose of

validating the soundness and strength of the valve

pressure containing and retaining structures.

Note: These structures include valve actuating

mechanisms that have a direct connection to the valve

internal subject to fluid test pressure within the valve

proper.” ISO 5208:2008(E)

Irrespective of the testing protocol, your customer will

call you if valve leaks through the pressure boundary.

It’s our obligation to learn from the occurrence and

continuously improve the supplier chain and validation

process when these events do occur.

Visually Detectible Leakage Through the Pressure Boundary Walls is not Acceptable

The receiving scenario:

• Customer gas tests new valve fresh from the crate

• Applies a liquid film solution to the closure element

• Wets the entire valve down with a liquid film solution

• Patiently observes until bubbles form on the cast body

What next? It’s your brand, and your opportunity.

Relative Cost of Testing Equipment

The cost of detecting a leak depends of the sensitivity of

detection. The greater the sensitivity the higher the cost.

Bubble Immersion Test:

Water must remain clear to retain the sensitivity of the

immersion test and changed at regularly scheduled

intervals

Low surface tension immersion liquids can be

accomplished by the addition of wetting agents into the

test water. The resulting test liquid will dramatically

reduce the radius of the bubble formed at the end of a

capillary leak.

“When a test liquid does not wet the solid surface around

the orifice of a leak, the bubble rim tends to spread away

from the leak orifice. This results in the formation of

larger bubbles.” (ASNT NDT Handbook 2nd Ed.)

Bubble Immersion Test:

“Use of low surface tension liquids might theoretically reveal

leakage rates in the range of 1/50 to 1/100 of the lowest

leakage rates detectable when bubbles are formed in water.”

(ASNT NDT Handbook 2nd Ed.)

Percentage

Additive (In

Immersion Water

Minimum Detectable Leakage

Rate with Nitrogen Gas at

120KPa (Gauge) or 18 psig

0 1 x 10-3 std cm3/sec

1 1 x 10-4

5 1 x 10-5

25 1x 10 -6

A good offence (prevention) is the best defense.

Dewpoint temperature is the temperature that gas can

hold no additional water vapor and condensation of

moisture takes place. Apply a dewpoint sensor to

monitor compressed air systems to retain test air

which is free of condensed moisture.

If the objective is to find minute porosity in cast or

welded structures, there are numerous tests utilizing

air or inert gas that will be more effective than tests

that use high pressure water.

Introducing the air prior to immersion in the detection

liquid will improve the leak test sensitivity, by avoiding

the capillary action of water into the pores of the

material. Water and other liquids can actually clog

leaks.

“The surface areas to be tested shall be free of oil,

grease, paint, or other contaminants that might mask

a leak. If liquids are used to clean the component or if

a hydrostatic or hydropneumatic test is performed

before leak testing, the component shall be dry before

leak testing.” 2007 ASME V

Alternatives to Bubble Leak Testing:

If the objective is to detect a bubble, why make

the bubble radius smaller?

Pressure Change Testing

The test sensitivity is established against known

commercially available calibrated leak device

A leak test technician monitors the color of the panel lights

to identify on a pass-fail basis

Advantage: Operator follows the defined sequence, and

close, prolonged observation for leaks is mitigated.

Disadvantage: The leak location is not identified.

Note: For automatic leak detection methods, “no visible leakage” is defined in MSS SP-61

as a leak no greater than 6.7x10-4 ml/sec. with a pressure differential of 80-100 psi for

valves NPS 8” & smaller.

The Test Procedure

A documented procedure to conduct a test

including the elements of the test, both essential

and nonessential variables.

When an essential variable is changed, the

procedure qualification is effected because the

sensitivity of the test is potentially impacted

Requirements

Example

Essential

Variables

Nonessential

Variables

Test solution X

Lighting intensity X

Post cleaning X

Pressurizing gas X

The Test Procedure Qualification

Preproduction testing conducted under controlled

conditions, which document the actual sensitivity and

reliability of the testing procedure in detecting leaks.

The procedure includes the parameters of the testing

process including but not limited to personnel

qualification requirements, how to prepare the item to

be tested, the method of application of the test

solution. Some other elements include test pressure,

test fluid, duration, lighting, applicable remote viewing

and qualification of that device.

Personnel Qualification & Record

Written procedure to establish the minimum

requirements for education, training, experience,

examination, and qualification of personnel

responsible for conducting testing.

Training is typically followed by both a written

examination and a practical demonstration of

competency where the results are recorded and

retained.

Requirements for retesting due to failing results

are defined.

Control Valve Seat Leakage vs. a Cup of Coffee

Liquid Test 4”

diameter seat

Leakage Rate

ml/min

Time to fill a 14

oz. cup of

coffee

ISO 5208 Third

edition Rate A

0 -

ISO 5208 Third

edition Rate B

0.06 A little less than

5 days

ISO 5208 Third

edition Rate C

0.18 About a day and

a half

ANSI/FCI 70-2-

2006 class V

0.55 12.5 hours

ISO 5208 Third

edition Rate D

0.60 11.5 hours

Summary and Conclusions:

Industrial valve customers are specifying casting examination

and upgrade, similar to requirements intended for special class

valves in ASME B16.34.

NDT methods such as radiography, magnetic particle

examination, liquid dye penetrant tests all have their strengths

and limitations.

To detect through wall capillary leaks formed during casting

solidification, in fabrication, and defect removal by welding, the

industry should consider changes which include greater

utilization of gas testing.

There’s an Opportunity to Improve the Standards

1. Require a low pressure gas shell test to reliably identify

small leaks, and do so prior to filling the potential

leakage capillaries with water during other tests.

2. Encourage the use of clear immersion fluids and wetting

agents for improved sensitivity of leak detection.

3. Address the protective coatings deployed to protect

ferrous materials and the sequence in which they are

applied with respect to pressure testing

The liquid shell test is known to be an efficient means to assure

the strength of pressure containing structures, yet this test does

less well in revealing small leak paths.

Requirements Overview ASME B16.34ASME B16.34-2009 Valves-Flanged, Threaded, and Welding End

Test Requirement Description of Test Requirement Additional Controls

Shell Gage pressure no less than 1.5 x >100 deg. F rating rounded up to next 25 psi

increment. Visually detectable leakage through the pressure boundary walls not

acceptable

In partially open position

Shell Test Duration NPS< 2” at least 15 sec.

2.5 <NPS<6” at least 60 sec.

8 <NPS<12” at least 120 sec.

14”< NPS at least 300 sec.

Test time is the period of inspection after the valve is fully prepared & is

under shell test pressure

Stem seal Stem seals shall be capable of retaining pressure at least equal to the 100 deg. F

ratings w/o visible leakage

LP Closure At mfr’s option gas test >80psi. may be substituted for HP closure test as follows:

Valve Size Pressure Class

NPS < 4” < 2500

NPS <12” < 300

Refer to Note 1

Closure test leakage acceptance criteria shall be by agreement between

manufacturer and purchaser

HP Closure Test shall not be less than 110% of the 100 deg F pressure rating

Refer to option for LP Closure above

Refer to Note 1

Closure test leakage acceptance criteria shall be by agreement between

manufacturer and purchaser

Closure Test Duration NPS < 2” at least 15 sec.

2 1/2” < NPS< 8” at least 30 sec.

10”< NPS < 18” at least 60 sec.

< 20” NPS at least 120 sec.

Backseat provision No

Double seating provision Pressure applied successively on each side

Visual examination of castings MSS SP-55

Directional sealing provision Test in direction producing the most adverse condition

Restricted Seating for less than the 100

deg. F rating

Test may be reduced to 110% of maximum specified closed position differential

pressure

Test Fluid Temperature <125 deg. F

Detection Fluids Water which may contain a corrosion inhibitor, kerosene, or other suitable fluid w/ a

viscosity not greater than water

Cautionary statement concerning gas shell testing hazards

End Clamping restrictions None identified

Leakage detection devices May be used for detecting leakage provided that they are used at the required

pressures

Manufacturer shall have demonstrated that test results are equivalent to

requirements

Surface protection Valves shall not be painted or otherwise coated with materials capable of sealing

against leakage before shell tests are completed

Chemical corrosion protection treatment is permitted

Allowance made for internal linings or coatings included in the design.

Refer to Note 2

Supplementary Examinations For Special Class Valves per mandatory examinations in appendix

Note 1: Closure tests shall follow the shell test except for valves NPS 4” and smaller w/ ratings Class 1500 & lower the closure test may precede the shell test when a gas closure is used.

Note 2: Refer to Code for assembled valves having bodies & bonnets or cover plates that have been separately tested

Requirements Overview API Standard 598, API Standard 598, Ninth Edition, September 2009

Test Requirement Description of Test Requirement Additional Controls

Shell Where applicable same as ASME B16.34. Additional valve materials included by NPS and

pressure Class Visually detectable leakage through the pressure boundary walls and any

fixed body joint is not permitted

When specified by the purchaser a high pressure

pneumatic shell test shall be performed after the shell

test. Test is at 110% of the max. allowable pressure

at 100 deg F. visible leakage is not allowed

Shell Test Duration < 2” NPS 15 sec. minimum

2.5 - 6” NPS 60 sec. minimum

8”- 12” NPS 120 sec. minimum

>14” NPS 300 sec. minimum

Test time is the period of inspection after the valve is

fully prepared & is under full pressure

Stem seal Leakage through the stem seals during the shell test shall not be cause for rejection.

However, stem seals shall be capable of retaining pressure at least equal to the 100 deg. F

ratings w/o visible leakage

Visible leakage through nonadjustable stem seals is

not permitted.

LP Closure Gas test at 60-100 psig

(refer to standard for applicability by valve type, size, material and pressure class

Refer to note 1

Multiple clarifications and restrictions concerning

testing protocol by valve type, size, material and

pressure class.

External forces that affect seat leakage prohibited

HP Closure 110% of maximum allowable pressure at (100 deg. F) or design differential pressure or test

pressure specified in Table 4 depending on valve size, Class and type.

Multiple clarifications and restrictions concerning

testing protocol by valve type, size, material and

pressure class

Refer to note 2:

Closure Test Duration < 2” NPS 15 sec. minimum (except for check valves API 594 60 sec. min.)

2.5 - 6” NPS 60 sec. minimum

8”- 12” NPS 120 sec. minimum

>14” NPS 120 sec. minimum

Backseat Test As applicable to valve type

A high or low pressure test at the manufacturers option

Excludes bellows seals. Multiple clarifications and

restrictions concerning testing protocol

Double Block & Bleed high pressure closure test Apply pressure successively to each side , monitor at position G

Visual examination of castings MSS SP-55

Supplementary Examinations Part 8, ASME B16.34 Optional

Directional sealing provision Apply pressure on pressure side only

Restricted Seating for less than the 100 deg. F

rating

Test at 110% of maximum specified closed differential

Test Fluid Temperature 41 deg F to 122 deg. F

Detection Fluids Air, inert gas, kerosene, or a noncorrosive liquid with a viscosity not higher than that of water.

When testing austenitic stainless steels the chloride content shall not exceed 100 ppm .

Low pressure closure and low pressure backseat shall

be air or inert gas.

End Clamping restrictions None

Leakage detection devices Allowed- when manufacturer can demonstrate and validate that the procedure yields

equivalent results

Surface protection Required protective coatings such as paint which may mask surface defects shall not be

applied to any surface before inspection or pressure testing

Allowance permitted for chemical conversion

processes

Note 1: Closure tightness requirements vary by valve type, size and seat material. For resilient seat valves the maximum allowable leakage is zero (0) Note 2: The high pressure closure test of resilient seated valves may degrade subsequent sealing performance in low pressure service” 9th Ed. API-598 9/2009

Requirements Overview MSS SP-61MSS SP-61-2009 Pressure Testing of Valves

Test Requirement Description of Test Requirement Additional Controls

Shell 1.5 x >100 deg. F design pressure rating rounded up to next 25 psi increment.

Visually detectable leakage through the pressure boundary walls is not

acceptable

Shell test precedes the closure test.

For a hydrostatic test there shall be no visible weeping or formation

of drops at the test press and for the duration of the test.

For air or gas testing no visible formation of bubbles in a water

immersion test or application of a leak detection fluid at the test

pressure and for the duration of the test.

Shell Test Duration < 2” NPS and smaller at least 15 sec.

2.5 - 8” NPS at least 60 sec.

10” & larger at least 180 sec.

Test time is the period of inspection after the valve is fully prepared

& is under full pressure

Stem seal Leakage through the stem seals during the shell test shall not be cause for

rejection. However, stem seals shall be capable of retaining pressure at least

equal to the 100 deg. F ratings w/o visible leakage

Visible leakage through nonadjustable stem seals is not permitted.

LP Closure Gas test at 60-100 psig

(refer to standard for applicability by valve type, size, material and pressure class

Acceptable leakage rate tabulated per NPS- Refer to note 1

Seat closure tests for NPS 4” and larger shall be conducted after

an acceptable shell test. For ASME B16.34 valves, requirements of

para. 7.2 from that Code apply.

HP Closure 110% of maximum allowable pressure at (100 deg. F) or design differential

pressure or test pressure specified in Table 4 depending on valve size, Class

and type.

Acceptable leakage rate tabulated per NPS-Refer to note 1

Seat closure tests for NPS 4” and larger shall be conducted after

an acceptable shell test. For ASME B16.34 valves, the

requirements of paragraph 7.2 from that Code apply.

Closure Test Duration < 2” NPS 15 sec. minimum except for check valves (API 594) 60 sec. min.

2.5 - 6” NPS 60 sec. minimum

8”- 12” NPS 120 sec. minimum

>14” NPS 120 sec. minimum

Backseat Test As applicable to valve type Excludes bellows seals. Multiple clarifications and restrictions

concerning testing protocol

Double seating provision Pressure applied successively to each side Alternate method for independent double seating provided for

Double Block and Bleed provision NA

Visual examination of castings NA

Directional sealing provision Pressure applied in the most adverse direction, and if marked for one direction

tested in the appropriate direction

Clarifications provided for valves with singular or symmetrical seat

and butterfly valves with offset stem design

Restricted Seating for less than the 100 deg. F rating Test at 110% of maximum specified closed differential

Test Fluid Temperature < 125 deg. F

Detection Fluids Air, inert gas or a liquid, such as water (which may include a corrosion inhibitor),

kerosene, or other fluid with a viscosity not higher than that of water.

End Clamping restrictions Loads are limited to those required to effectively seal valve ends

Leakage detection devices Allowed- Manufacturer must be able to demonstrate equivalent results to the

requirements of this standard

Definition shall be considered equivalent to a leak of 6.7x10-4

ml/sec. with a pressure differential of 80-100 psi for valves NPS 8”

and smaller

Surface protection Must be shell tested prior to painting Allowance permitted for chemical corrosion protection treatment

such as phosphatizing and lining may be applied prior to shell test

Supplementary Examinations NA

Note 1: For valves having a seat closure member that uses a compliant material, there shall be no visible leakage for the duration of the test.

Requirements Overview ISO 5208- Industrial Valves, Third Ed. 2008-08-01- Pressure testing of metallic valves

ISO 5208- Industrial Valves, Third Ed. 2008-08-01- Pressure testing of metallic valves

Test Requirement Description of Test Requirement Additional Controls

Shell 1.5 x (38 deg C) 100 deg. F CWP rating minimum Visually detectable leakage from any

external surface of the shell is cause for rejection

A liquid test is required.

Stem seal leakage is permitted provided that there is no visually

detectible leakage at 110% CWP

Shell Test Duration Valve Size

DN<50(2”) 15 sec. minimum

65<DN<150(2.5”- 6”) 60 sec. minimum

200<DN<300(8”-12”)180 sec. minimum

DN>350 (14”) 300 sec. minimum

Test time is the period of inspection after the valve is fully prepared & is

under test pressure

Stem seal No visually detectible leakage at 110% CWP during a liquid test

LP Closure Gas test at 6 bar +/-1 bar(72.5-101.5 psi)

(refer to standard for applicability by valve type, size, material and pressure class)

Successful completion of an optional test does not relieve the

manufacturer from successful completion of required test.

HP Closure Liquid test at 110% of CWP minimum

(refer to standard for applicability by valve type, size, material and pressure class)

In the case of resilient seated vales, a high pressure test mat degrade

subsequent sealing performance in low pressure applications

Closure Test Duration Valve Size

DN<50(2”) 15 sec. minimum ( except 60 sec. for check valves)

65<DN<150(2.5”- 6”) 60 sec. minimum

200<DN<300(8”-12”)120 sec. minimum

DN>350 (14”) 120 sec. minimum

Backseat Test Optional when so specified by the purchaser for relevant valves. not required for bellows

stem seals

A liquid test at 110% of valve CWP minimum. Multiple

recommendations for testing protocol

Double seating provision Provides for closure testing progressing for gat ball and plugs valves

Double Block and Bleed provision High pressure closure test is required, low pressure closure test is optional

High pressure pneumatic shell test Optional Test fluid is gas at 110% of CWP, minimum. Liquid shell test should be

performed first. Continuous formation of bubbles from external surface

is cause for rejection

Directional sealing provision Testing protocol defined for valves with a unidirectional flow marking

Restricted Seating for less than the

100 deg. F rating

Per agreement between the purchaser and manufacturer. Test at a pressure of 1.1 x the

design differential pressure

I.D. plate with limitation required

Temperature >5 deg. C < 40 deg. C (104 deg. F)

Detection Fluids Water (which may contain a corrosion inhibitor), kerosene, or other appropriate liquid fluid

having a viscosity not greater than that of water.

Air or other suitable gas

When water is the test fluid the chloride content a the shall not exceed

100 ppm when testing austenitic stainless steels

Purchaser may specify that a wetting agent be added to the water used

as a test fluid

End Clamping restrictions When end clamping devices are used, the manufacturer shall be able to demonstrate that,

during the valve closure test, they do not serve to reduce the resultant leakage

Leakage detection devices Allowed- Manufacturer shall be capable of demonstrating equivalence of the system with the

requirements of this international standard

Surface protection Shall not be externally painted or coated with materials capable of sealing against leakage

from external surfaces of the shell. Internal linings and coatings that form a design feature

are permitted to be tested with them in place

Chemical corrosion protection treatments prior to shell testing are not

mentioned.

Location Pressure tests shall take place either at the site of the valve manufacture, or at a test facility

under the supervision of the valve manufacturer.

Note 1: For valves having a seat closure member that uses a compliant material, there shall be no visible leakage for the duration of the test.

Requirements Overview API Standard 6D, 23rd Edition, April 2008- Specification for Pipeline Valves

API Standard 6D, 23rd Edition, April 2008- Specification for Pipeline Valves

Test Requirement Description of Test Requirement Additional Controls

Shell 1.5 or more times the 100 deg F pressure rating. No visible

leakage is permitted during the test.

Provision to remove relief valve valves when applicable

Shell Test Duration 1/2”- 4” NPS… 2 minutes minimum

6”-10” NPS …..5 minutes minimum

12”-18” NPS. .15 minutes minimum

>20” NPS….. 30 minutes minimum

Provision to test the relief valve connection

Stem seal Leakage through the stem seals not permitted

LP Closure Not applicable- Alternative inert gas seat test is allowed after shell

testing by agreement and remains a high pressure test

HP Closure Shall not be less than 1.1 times the100 deg F pressure rating Soft seated and lubricated plug valves shall not exceed ISO 5208 rate A (no

visible leakage) Metal seated valves shall not exceed ISO 5208-1993, Rate D.

Seat test procedures for block valves described within the standard.

Alternative gas pressure tests may be specified by the purchaser.

Closure Test Duration 1/2”-4” NPS….2 minutes minimum

> 6” NPS……..5 minutes minimum

Backseat Test When applicable and packing gland loosened unless a test port is

provided

1.1 x 100 deg F pressure rating, no leakage permitted. Test is performed prior

to the hydrostatic shell test.

Double Block & Bleed

Provision

With valve 1/2 open the valve and cavity completely filled with test

fluid. The valve is closed, body vent opened to allow excess fluid to

drain.

Test pressure applied simultaneously from both ends. Seat tightness is

monitored via overflow through the cavity drain connection.

Refer to note 1:

Unidirectional Provision Cavity completely filled with test fluid, valve is closed and test

pressure applied at appropriate end of valve

Monitored at body cavity vent or drain connection or downstream end of valve

Visual examination of

castings

MSS SP-55

Supplementary

Examinations

Optional Per normative annex

Bidirectional sealing

provision

Cavity completely filled with test fluid, valve is closed and test

pressure applied successively at both ends of valve

Monitored at body cavity vent or drain connection or downstream end of valve

Temperature 5 deg C -40 deg C

Detection Fluids Fresh water or by agreement light weight oil with a viscosity not

exceeding that of water

If the valve has wetted components of austenitic or duplex stainless steels

then chloride content shall not exceed 30 ppm by mass

End Clamping restrictions No restrictions

Leakage detection devices Not in scope

Surface protection Testing shall be carried out prior to coating of the valves

Note 1: Testing protocol also provided for double isolation and bleed DIB-1 (both seats bi-directional) and double isolation and

bleed DIB-2(one seat uni-directional and one seat bidirectional)

Requirements Overview ANSI/FCI 70-2-2006 American National Standard, Control Valve Seat Leakage, Fluid Controls Institute Inc.

ANSI/FCI 70-2-2006 American National Standard, Control Valve Seat Leakage, Fluid Controls Institute Inc.

Test Requirement Description of Test Requirement Additional Controls

Seat leakage classes defined for

control valves

Defines test media, temperature

range, pressure ranges and leakage

flow

Actual leakage is measured and compared to calculated

values as a % of value capacity or volume over time for

applicable orifice or seat diameter according to seat

diameter depending on leakage class