Valve Inspection & Testing (API 598)

 

Valve are mechanical devices specially designed to direct, start, stop, mix or regulate the flow, pressure or temperature of pressure fluid.

Below the standard for inspection & testing based on API 598.

 

A.     VISUAL  

·        Check Casting of body (no damage, Heat No)

·        Check Bonnet (no damage, Heat No)

·        Check Disc (no damage, Heat No)

·        Check Dimensional

 

B.     TESTING REQUIREMENT

 

·        TESTING EQUIPMENT

1.       Check calibration certificate

2.       Check Equipment

3.       Performance of equipment.

 

·        TEST REQUIRED

 

 

Test Description

Valve Type

 

 

Gate

 

Globe

 

Plug

 

Check

 

Floating Ball

Butterfly & Trunnion-mounted ball

Shell

Required

Required

Required

Required

Required

Required

Backseat

Required

Required

N/A

N/A

N/A

N/A

Low Pressure Closure

Required

Optional

Required

Alternative

Required

Required

High Pressure Closure

Optional

Required

Optional

Required

Optional

Optional

 

·        TEST FLUID

1.       For shell, high-pressure backseat, and high-pressure closure tests, the test fluid shall be air, inert gas, kerosene, water, or a non corrosive liquid with a viscosity not higher than that of water.

2.       For the low-pressure closure and low pressure back-seat test, the test fluid shall a air or inert gas.

3.       When air or gas is used for closure, shell, or backseat tests, the valve manufacturer shall be capable of demonstrating the adequacy of the method of leakage detection.

4.       Water used for any test may contain a water-soluble oil or a rust inhibitor. When specified by the purchaser, a wetting agent shall be included in the water. For testing of austenitic stainless steel valves, water with chloride content not exceeding 100 parts per million shall be used. The valve manufacturer shall be able to document the chloride content.

 

·        SHELL TEST PRESSURE

Valve type

Class

Shell Test

Pressure (Minimum)

Psi

Bar

Ductile iron

150

400

26

 

300

975

66

Cast Iron

125

 

 

NPS 2-12

 

350

25

NPS 14-24

 

265

19

Cast Iron

250

 

 

NPS 2-12

 

875

61

NPS 14-24

 

525

37

Steel

 

 

 

Flange & butt-weld

150-2500

a

 

Screwed & socket-weld

800

b

 

 

155-2500

c

 

NOTE

a. Per ASME B16.34

b. For class 800 valves, the shell test pressure shall be 1½ times the pressure

    rating at 100°F (38°C), Rounded off to the next higher increment of 25

    Pounds per square inch gauge (or 1 bar) (see Table 2 of API Standard 602)

 

·        OTHER TEST PRESSURE

Test

Minimum Test Pressure

 
 

Psi

Bar

 

Valve except butterfly & check

 

 

 

High pressure closure & backseat

 

 

Low pressure closure & backseat

 60 – 100

4 – 7 

 

Butterfly Valve

 

 

 

High pressure closure

 C

 

 

Low pressure closure

 60 – 100

4 – 7 

 

Check Valve

 

 

 

High pressure Closure

 

 

 

   Clas 125 (cast iron)

 

 

 

      NPS 2 – 12

200

14

 

      NPS 14 – 48

150

11

 

   Clas 250 (cast iron)

 

 

 

      NPS 2 – 12

500

35

 

      NPS 14 – 48

300

21

 

   Clas 150 (ductile iron)

250

17

 

   Clas 300 (ductile iron)

640

44

 

   Carbon, alloy, stainless steel,

 

 

 

   and special alloys

b

-

 

Low pressure Closure

60 – 100

6 – 7

 

 

 

 

 

NOTE

 

a. The backseat test is required for all valves that have this feature.

 

b. 110 percent of maximum allowable pressure at 100°F (38°C) in accordance

 

    with the applicable purchase specification

 

c. 110 percent of design differential pressure at 100°F (38°C) in accordance

 

    with the applicable purchase specification

 

 

C.     TESTING PROCEDURE

 

·        SHELL TEST

The shell test shall be performed by applying the pressure inside the assembled valve with the valve ends close, the valve partially open, and any packing gland tight enough to maintain the test pressure, thereby, except for bellows seal valves, testing the stuffing box. Nonadjustable shaft seals (O rings, single rings, and the like) shall not leak during the shell test.

 

·        BACKSEAT TEST

The backseat test is required for all valves, except for bellows seal valves, that have the backseat feature and shall be performed by applying pressure inside the assembled valve with the valve ends closed, the valve fully open, and the packing gland loose. The backseat test may be performed immediately after the shell test, and all packing glands shall be retightened after the backseat test.

 

·        LOW PRESSURE CLOSURE

The low-pressure closure test shall be performed with the sealing surfaces clean and free from oil, grease, and sealant, If necessary to prevent galling, the sealing surfaces may be coated with a film of oil that is not heavier than kerosene. This requirement does not apply to a valve that uses a lubricant as its primary seal (for example, lubricated plug valves).

 

·        HIGH PRESSURE CLOSURE

The procedure for the high-pressure closure test shall be the same as the procedure for the low-pressure closure test except that, in the case of a liquid test, leakage shall be detected when drops.

 

·        TEST DURATION

 

Valve Size (NPS)

Minimum Test Duration (second)

 

SHELL TEST

Backseat

CLOSURE

 

Check Valve (API Std 594)

Other  Valve

Check Valve (API Std 594)

Other  Valve

 
 

≤2

60

15

15

60

15

 

2½ – 6

60

60

60

60

60

 

8 – 12

60

120

60

60

120

 

≤ 14

120

300

60

120

120

 

 

·        MAXIMUM ALLOWABLE LEAKAGE RATES FOR CLOSSURE TEST

 

Valve Size (NPS)

All resilient Seated valves

All metal-seated valves except Chechk

Metal-seated Check Valves

 
 

Liquid test

Gas test

Liquid test

Gas test

 

(drop per minute)

(bubbles per minutes)

(drop per minute)

(bubbles per minutes)

 

≤2

0

0b

0b

c

d

 

2½ – 6

0

12

24

c

d

 

8 – 12

0

20

40

c

d

 

≤ 14

0

28

56

c

d

 

NOTE

 

 

 

 

 

 

a. For the liquid test, 1 millimeter is considered equivalent to 16 drops.
b. There shall be no leakage for the minimum specified test duration (see Table 4). For liquid test, O drop means no visible leakage per minimum specified test
duration. For gas test, O bubble means less than 1 bubble per minimum specified test duration.
c. The maximum permissible leakage rate shall be O. 18 cubic inch (3 cubic centimeters) per minute per inch of nominal pipe size.
d. The maximum permissible leakage rate shall be 1.5 standard cubic feet (0.042 cubic meter) of gas per hour per inch of nominal pipe size.
e. For check valves larger than NPS 24, the allowable leakage rate shall be per agreement between purchaser and manufacturer.

 

 

 

6 Responses

  1. good job

  2. Dear Sirs,

    Please introduce my self, my name is Zamroni and my company name is PT. DYNATECH INTERNATIONAL.
    My company is a supplier for Material testing.
    At this time we have an inquiry from my customer (Indonesia Power Plant) for NDT (Non Destructive Test) Portable/Mobile.
    My customer want to check whether inside Valve is damage or crack.
    For your information that the diameter of Valve is 1 meter minimum and the thickness of Valve range is 10 – 20 cm.
    Please inform me what kind of Instruments/Equipment can be used for this application.
    Please send us catalogs/brochures in pdf file.
    We are waiting your soonest reply.
    We will appreciate all you have done for us.
    Thank you for your kindly attention and good cooperation.

    Thanks & regards,
    Zamroni

  3. Dear sir
    please let me know what is the allowable drop(leakage) for GGC valve

  4. dear pak lukman,

    salam kenal, sangat bagus artikel yg bapak buat, mohon ijin copas artikel nya pak untuk bekal di lapangan. terima kasih

  5. Dear Pak Lukman,

    I need your advice regarding PRV inspection,
    Did API RP 576 explain all technic to calibrate/re-caibrate the PRV?.
    Do you have a simple procedure/SOP regarding those inspection, just like you done on Valve Inspection & Testing (API 598)?

    Thanks and Regard,
    MY

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