API St 598-2009 pdf download.Valve Inspection and Testing.
3.6 double block and bleed valve Valve with two seating surfaces that when in the closed position, blocks flow from both valve ends when the cavity between the seating surfaces is vented through a bleed connection provided in the body cavity. 3.7 nominal pipe size NPS An alpha numeric designation of size that is common for components used in a piping system, used for reference purposes, comprising the letters NPS followed by a dimensionless number indirectly related to the physical size of the bore or outside diameter of the end connection as appropriate. The dimensionless size identification number following NPS does not represent a measurable value and is not used for calculation purposes except where specified in ASME B16.34. Prefix NPS usage is applicable to steel valves bearing class designations. 3.8 shell test 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. 3.9 visually detectable leakage Leakage during a valve pressure test, either through or past a pressure boundary or closure member that is validated by normal vision. 4 Inspection, Examination, and Supplementary Examination 4.1 Inspection at the Valve Manufacturer’s Plant The purchaser shall specify in the purchase order his intention to inspect valves and witness tests and examinations at the valve manufacturer’s plant. The purchaser’s inspector shall have free access to any part of the plant concerned with manufacture of the valves whenever work on the order is under way. 4.2 Inspection Outside the Valve Manufacturer’s Plant When the valve purchaser specifies that the inspection will include shell components manufactured at locations other than the valve manufacturer’s plant, these components shall be subject to the valve purchaser’s inspection at the location where they are manufactured.
4.5 Examination 4.5.1 A visual examination shall be performed by the valve manufacturer on all castings of bodies, bonnets, covers, and closure elements to assure conformance with MSS SP-55. 4.5.2 Each valve shall be examined to assure compliance with this standard and the referenced purchase specification (e.g. API 599). 4.5.3 All examinations shall be performed in accordance with written procedures that comply with the applicable standards. 4.6 Supplementary Examination Supplementary types of examination are required only if specified in the purchase order and only to the extent specified. Magnetic particle, radiographic, liquid penetrant, and ultrasonic examination of steel castings or forgings shall be in accordance with Part 8 of ASME B16.34 or with the purchaser’s own procedures and acceptance criteria, if so specified. These examinations shall be made by the valve manufacturer subject to witnessing by the purchaser’s inspector. 5 Pressure Tests 5.1 Test Location Pressure tests shall be performed by the valve manufacturer at the valve manufacturer’s plant or at a facility mutually agreeable to both the manufacturer and purchaser. 5.2 Test Equipment The equipment used by the valve manufacturer to perform the required pressure tests shall not apply external forces that affect seat leakage. If an end-clamping fixture is used, the valve manufacturer shall be able to demonstrate that the test fixture does not affect the seat sealing capability of the valve being tested. End clamping is allowed for valves designed to function between mating flanges, such as wafer check and wafer butterfly valves. 5.3 Tests Required 5.3.1 The pressure tests listed in Table 1 or Table 2 shall be performed on each valve in accordance with written procedures that comply with this standard. 5.3.2 At the manufacturer’s option, the backseat test for valves that have the backseat feature may be either a high- pressure or a low-pressure test unless stated otherwise in the purchase order.