Testing Specification in API 6DSS
Each valve shall be tested in accordance with this clause prior to shipment. The purchaser shall specify which particular supplementary tests in annex C shall be performed, together with the frequency of testing.
Tests shall be performed in the sequence used in this clause for specifying the test requirements. Shell pressure tests shall be carried out before painting of the valves (such as China ball valve).
Test fluids shall be fresh water which may contain a corrosion inhibitor and, by agreement, antifreeze. The chloride content of test water for austenitic and ferritic-austenitic (duplex) stainless steel body/bonnet valves shall not exceed 30 µg/g (30 ppm). Valves for gas service shall also be subjected to a gas test in accordance with C.4.
Valves shall be tested with the obturator or seat faces free from sealant and lubricant. A light lubricant, of maximum viscosity SAE 10W, may be used to aid assembly of other components.
Tests specified with the valve half-open may also be performed with the valve fully open provided the body cavity is simultaneously filled and pressurized through a cavity connection.
Methods for monitoring pressures and/or leakage shall be provided when valve body connections are not available for direct monitoring.
An adequate stabilization period shall be allowed for all pressure tests. After stabilization, the pressure source shall be isolated from the valve.
A chart recorder shall be used for all pressure tests above 1 MPa (10 bar).
Pressure tests shall be performed in accordance with documented procedures.
Valves (from China gate valve supplier etc. shall be drained of test fluids and, where applicable, lubricated before shipment.
10.2 Hydrostatic shell test
Perform hydrostatic shell testing on the fully assembled valve, including pipe pups if applicable, prior to painting.
Close off valve ends and place the obturator in the partially opened position during the test. The method of closing
the ends shall permit the transmission of the full-pressure force acting on the end blanks to the valve body, unless otherwise agreed. If present, remove external relief valves and plug their connections.
The test pressure shall be 1,5 or more times the pressure rating determined in accordance with 6.2 for materials at 38 °C (100 °F). The duration shall not be less than that specified in Table 8.
DN 50 to 100 ( NPS 2 to 4) Test duration: 2h
DN 150 to 250 ( NPS 6 to 10) Test duration: 4h
DN 300 and bigger (NPS 12 and bigger) Test duration: 6h
No visible leakage is permitted during the hydrostatic shell test. There shall be no variation in pressure that cannot be accounted for by temperature fluctuations.
If the pressure rating of the pipe pups is insufficient for the hydrostatic shell test pressure, then the pups shall be welded to the valve following the valve shell test and the valve and pup(s) tested at a pressure to be specified by the purchaser.
Pressure protectors or caps shall be tested at a pressure no less than the hydrostatic shell test pressure. The test duration shall be a minimum of 2 h.
10.3 Operational/functional test
10.3.1 Manual valves
Operate each manual or ROV-operated valve, excluding check valves (made by China wafer check valve supplier), two times while subjecting to the differential pressure specified in 6.8. Operate the valve for each appropriate condition defined in 10.4. Valves requiring input forces exceeding that specified in 6.12 or that fail to seal after operation shall be rejected.
10.3.2 Power-operated/actuated valves
Operate power-operated/actuated valves, excluding check valves, two times while subjecting to the differential pressure specified in 6.8. Operate the valve for each appropriate condition defined in 10.4 and measure the thrust or torque. Values for thrust or torque shall not exceed the predicted manual or power values specified in 6.19.1.
10.3.3 Check valves
Operate each check valve fitted with an operating mechanism close-open-close five times while the entire body cavity is subjected to the rated pressure listed in 6.2. Valves that fail to operate or fail to seal after cycling shall be rejected.
10.3.4 Sequence of testing
Operational/functional tests may be performed in conjunction with hydrostatic seat testing specified in 10.4. Seat sealing integrity shall be verified after all operational/functional testing.
10.4 Hydrostatic seat test
Remove lubricants from seats and obturator sealing surfaces, unless otherwise agreed.
10.4.2 Test pressure and duration
The test pressure for all seat tests shall not be less than 1,1 times the pressure rating as determined in accordance with 6.2 for material at 38 °C (100 °F). The test duration shall be in accordance with Table 9.
DN 50 to 100 ( NPS 2 to 4) Test duration: 5 minutes
DN1 50 to 150 ( NP6 and bigger) Test duration: 15 minutes
10.4.3 Acceptance criteria
Leakage for soft-seated valves from China valve supplier shall not exceed ISO 5208 Rate A (no visible leakage). For metal-seated valves the leakage rate shall not exceed ISO 5208 Rate D, except that the leakage rate during the seat test in 10.4.4.5.2 shall not be more than two times ISO 5208 Rate D. Other leakage rates shall be by agreement. The test procedures for various types of block valves are given in 10.4.4.
10.4.4 Test procedures for block valves
10.4.4.1 Uni-directional valve
With the valve half open, completely fill the valve and its cavity with test fluid. Then close the valve and apply test pressure to the appropriate end of the valve.
Monitor leakage from each seat via the valve body cavity vent or drain connection, where provided. For valves without body cavity or drain connection, or downstream seated valves, monitor seat leakage at the respective downstream end of the valve (the valve end downstream of the pressurized test fluid).
10.4.4.2 Bi-directional valve
With the valve half-open, completely fill the valve and its cavity with test fluid. Then close the valve and apply test pressure successively to both ends of the valve.
Monitor seat leakage from each seat via the valve body cavity vent or drain connection, where provided. For valves without body cavity vent or drain connection, monitor seat leakage from the respective downstream end of the valve.
10.4.4.3 Twin-seat valve (such as China trunnion mounted ball valve), both seats bi-directional, test each seat in both directions.
Remove cavity relief valves, if fitted. Fill the valve and cavity with test fluid, with the valve half-open, until the test fluid overflows through the cavity relief connection.
To test for seat leakage in the direction of the cavity, close the valve. Apply the test pressure successively to each valve end to test each seat separately from the upstream side. Monitor leakage via the valve cavity pressure relief, body cavity drain or vent connection.
Thereafter, test each seat as a downstream seat. Drain both ends of the valve and fill the valve cavity with test fluid. Apply pressure while monitoring leakage through each seat at both ends of the valve.
10.4.4.4 Twin-seat valve, one seat uni-directional and one seat bi-directional
10.4.4.4.1 Uni-directional seat
With the valve half-open, fill the valve and the test cavity completely with test fluid until fluid overflows through the valve cavity vent connection. Then close the valve and open the vent valve on the test closure to allow fluid to overflow, or remove the test closure on the downstream end of the valve. Then apply the test pressure to the upstream end (uni-directional seat end) and monitor leakage from the cavity connection. If leakage is also occurring through the downstream seat, take the upstream seat leakage as the sum of the leakage measured from the cavity and the downstream connections.
10.4.4.4.2 Bi-directional seat
Repeat the test in 10.4.4.4.1 to test the bi-directional seat in its upstream-sealing direction.
To test the bi-directional seat in its downstream-sealing direction, blank off both ends of the valve. With the valve half-open, completely fill the valve with test fluid and pressurize to the test pressure. Then close the valve and allow test fluid to overflow from a connection on the test closure fitted to the end of the valve at the bidirectional seat end (i.e. downstream of the bi-directional seat). Maintain the test pressure on the cavity connection while monitoring seat leakage of the bi-directional seat at the overflow connection on the downstream test closure.
10.4.4.5 Double-block-and-bleed valves
10.4.4.5.1 Single-seat test
With the valve half-open, completely fill the valve and its cavity with test fluid. Then close the valve and open the valve body vent valve to allow excess test fluid to overflow from the valve cavity test connection. Then apply the test pressure to one end of the valve and release the pressure at the other end. Repeat this test for the other valve end.
Monitor seat tightness during each test via overflow from the valve cavity connection.
10.4.4.5.2 Double-block seat test
With the valve half open, completely fill the valve and its cavity. Then close the valve and open the valve body vent valve to allow excess test fluid to overflow from the valve cavity test connection. Apply the test pressure simultaneously from both valve ends.
Monitor seat tightness via overflow through the valve cavity connection.
The tests in 10.4.4.5 may be performed in any order by the manufacturer.
10.4.4.6 Check valves (such as China cast steel check valve)
Apply the pressure in the direction of the required flow blockage.
10.4.4.7 Installation of body connections after testing
On completion of the testing, fit pressure-containing parts, such as vent or drain plugs and cavity relief valves, in accordance with documented procedures.
10.5 Cavity relief test
If a body cavity relief test is specified by the purchaser, each valve shall be tested in the closed position. If the cavity over-pressure protection in both open and closed position is achieved by a hole in the obturator, or a hole around a seat seal, cavity testing is not required.
10.5.2 Closed position test
Fill the valve in the half-open position with water. Close the valve and allow water to overflow from the test connection at each end of the valve. Apply pressure to the valve cavity until one seat relieves the cavity pressure into the valve end, noting the pressure at which the cavity relieved. Close the test connection at this end, and continue to apply pressure to the cavity until the second seat relieves, noting the relieving pressure. Failure to relieve at a cavity pressure between 0,1 and 0,33 times the valve pressure rating as determined in accordance with 6.2 for material at 38 °C (100°F) is cause for rejection.
NOTEThe second seat relief is not possible with certain valve types (e.g. gate valves and ball valves where one seat is bi-directional).
10.6 Pneumatic seat test
The seat test in 10.4 shall be repeated at a test pressure of (550 ± 50) kPa [(5,5 ± 0,5) bar]. The test medium shall be air or nitrogen. For soft-seated valves, the leakage rate shall not exceed ISO 5208 Rate A (no visible leakage).
For metal-seated valves (such as China metal seated ball valve, the leakage rate shall not exceed ISO 5208 Rate D.
The valve shall be drained of test fluid prior to the start of the pneumatic seat test.
10.6.2 Test duration
The seat test duration shall be as specified in Table 9.
By Kevin Tsai from Relia Valve-China DIN valve supplier and API valve supplier.
Socket Welding Floating Ball Valves NPT Ends with Locking Device
Types of Flanges Used for Ball Valves