Valve Inspection & Testing

Transcription

1 Inspection & Testing in accordance with API 598 Valve Inspection & Testing Shell Test (Body Hydro Test): - Each valve shall be tested in accordance with ASME B for ASME valves. Shell test pressure shall not be less than 1.5 time at 38 0 C (100 0 F) of the pressure rating rounded of the next higher 1bar (25psi) increment. The test shall be made with the valve in partially open position. Test media: - Shell test shall be made with water contain corrosion or rust inhibitor. Test fluid temperature shall not exceed 50 0 C (125 0 F). Acceptance Criteria: - Visually detectable leakage through the pressure boundary is not acceptable. Body, bonnet, cover, gasket joint, stem seals, packing shall be capable of retaining pressure up to 38 0 C (100 0 F) pressure rating without visible leakage. Duration of Required Test Pressure Valve Size Minimum Test Duration ( Seconds) 1 NPS Shell Backseat (For valves with Backseat Features) Closure Check Valves (API594) Closure Other Valves 50 (2) to 150 (2.1/2 to 6) to 300 ( 8 to 12 ) (14 ) The test duration is period of inspection after valve is fully prepared & is under full pressure. High Pressure Closure Test (Seat Hydro Test):- Result of the test confirms the capacity of valve design, it is an optional test but mandatory for valve to pass the test. Test pressure shall be 110% of maximum allowable pressure at 38 0 C (100 0 F). Test media: - Test shall be made with water contain corrosion or rust inhibitor. Test fluid temperature shall not exceed 50 0 C (125 0 F). Low Pressure Closure Test (Air or pneumatic Test):- Low Pressure Closure test performed with air at 4 to 7 bar pressure. Acceptance Criteria: - for both high & low pressure closure test, visual evidence of leakage through the disk, behind seat rings, from shaft seals or any structural damage is not permitted. Note: - 1) Test shall be performed with seat sealing surface interface clean, free from oil, grease & sealant. 2) The backseat test is required for all valves that have this feature

2 Maximum allowable Leakage Rates for Closure Tests as per API 598 (mm) Valve Size NPS (in.) All Resilien t Seated Valves Metal Seated Valves Except Check Liquid Test a (drops/ min.) Gas Test a (bubbles/ min.) Liquid Test (cc/min) Metal Seated Check valves Gas Test ( m 3 /h) Gas Test ( ft 3 /h) 50 (2) 0 0 b 0 b / a For the liquid test, 1ml is considered equivalent to 16 drops. For liquid test, 0 drops means no visible leakage per minimum specified test duration. For gas test, 0 bubbles means less than 1 bubble per minimum specified test duration.

3 Inspection & Testing in accordance with BS EN Shell Test (Body Hydro Test): - Test pressure for each valve shall be a minimum of 1.5 times the allowable pressure at room temperature. Test media: - Shell test shall be made with water contain corrosion or rust inhibitor. Acceptance Criteria: - Visually detectable leakage from any external surface of the shell is not permitted. Leakage from the operating mechanism sealing is permitted at the shell test pressure provided that there is no visual detectable leakage when the test pressure is 1.1 times the allowable pressure at room temperature. Minimum Test Duration for Shell Tests Nominal Size Production Test& Acceptance Test (s) Type Test ( min ) Up to From 65 to & above Seat Tightness Test : - Test pressure shall be a minimum of 1.1 times the allowable differential pressure at room temperature, except that if the test fluid is gas, the test pressure may be lower of 1.1 times the allowable differential pressure at room temperature or ( 6± 1) bar for valves:- Size up to 80 for all pressure ratings Size above 80 & up to 200 for pressure ratings up to PN40 & up to Class300. Minimum Test Duration for Seat Tightness Tests Production Test & Acceptance Test Type Test Nominal Size Metal Seated Valves Soft Seated valves All Valves Liquid Gas Liquid or Gas Liquid or Gas Up to 50 15s 15s 15s 10min 65 to s 15s 15s 10min 250 to s 30s 30s 10min 500 & above 120s 30s 60s 10min

4 Acceptance Criteria: - As per below table. Maximum Allowable Seat Leakage for each leakage rate in cubic millimeters per second Test Fluid Rate A Rate B Rate C Rate D Rate E Rate F Rate G Liquid No visually detectable Gas leakage for duration of 0.3 x 3.0 X 30 X 0.01 x 0.03 x 0.1 X 0.3 X 1.0 X 2.0 X 300 X 3000 x 6000 x the test Note 1- The leakage rates only apply when discharging to room temperature. Note 2 No visually detectable leakage means no visible weeping or formation of drops or bubble and is lower leakage rate than Rate B. Inspection & Testing in accordance with ANSI / FCI 70 2 ANSI / FCI 70 2 classified valve leakages are as follows: Leakage Class Test Media Test Pressure Maximum Seat Leakage Class I Water None No Test Required Class II Class III Class IV Class V Class VI Clean Air or Water at C ( F ) Air / Nitrogen / Water C ( F ) Clean Air / Nitrogen C ( F ) 3 4 bar or ±5% of max. operating differential pressure, whichever is less 3.5 barg ( 50psi ) or ±5% of max. service Pressure drop. 3.5 barg ( 50psi ) or ±5% of max. service Pressure drop. 0.5% of Rated Valve Capacity 0.1% of Rated Valve Capacity 0.01% of Rated Valve Capacity 5 x 10-4 ml (0.0005ml) per minute per inch of seat diameter per psi differential As per below Table Nominal Seat Dia. ml per minute Bubble per min. 26 ( 1 ) 38 (1.5) 51 (2) 64 (2.5) 76 (3) 102 (4) 152 (6) 203 (8) 250 (10) 300 (12) 350 (14) 400 (16)

5 Inspection & Testing in accordance with ISO 5208 Shell Test (Body Hydro Test): - Test pressure for each valve shall be a minimum of 1.5 times the CWP (Cold Working Pressure). Test media: - Shell test shall be made with water contain corrosion or rust inhibitor at C to 38 0 C temperature. Acceptance Criteria: - Visually detectable leakage from any external surface of the shell is cause for rejection. Minimum Duration for Pressure Tests Minimum Test Duration B (s) Valve Size Shell Optional Backset Closure All Valves When Relevant Isolation Valves Check Valves B - The test duration is the period of time for inspection after the test valve is fully prepared and under test pressure. Backseat & Closure Test (Seat Hydro Test):- Test pressure shall be 1.1 of CWP (Cold Working Pressure). Test media: - The test shall be made with water contain corrosion or rust inhibitor at C to 38 0 C temperature. Low Pressure Closure Test (Air or pneumatic Test):- Low Pressure Closure test performed with air at 6 bar ±1 bar pressure. CONTINUED ON NEXT PAGE.

6 Acceptance Criteria: At backseat test, visually detectable leakage from any external interface of the shell, seat, and stem is cause for rejection, other given in below table. Test Fluid Unit Leakage Rate Rate A Rate AA Rate B Rate C Rate CC Rate D Rate E Rate EE Rate F Rate G Maximum Allowable Closure Test leakage Rate Gas Liquid Bubbles/s mm 3 /s Drops/s mm 3 /s No visually Detectable leakage for duration of the test x 0.18 x x x x 0.3 x x 0.01 x x 3 x x 0.03 x x 22.3 x x 0.08 x x 30 x x 0.1 x x 300 x x 0.3 x x 470 x x 0.39 x X 3000 x x 1 x x 6000 x x 2 x Note for above Table:- Note 1:- The leakage rates only when discharging test fluid to the atmosphere. Note 2:- The closure leakage rate that applies is either that identified in a valve product standard or leakage rate identified in a purchaser s valve procurement purchase order that is more stringent than that specified in the product standard. Note 3:- The meaning of No visually detectable leakage is that there is no visible weeping or leakage in the form of drop or bubbles. Note 4:- There is a loosely defined correspondence between the leakage rate acceptance values of API 598 and the leakage values Rate A as applied to 50, Rate AA- Gas & Rate CC Liquid for other than metal seated check valves and for check valves Rate EE-Gas and Rate G- Liquid. Rates A, B, C, D, E, F and G correspond to values in EN