API STD 600:2001 pdf download

API STD 600:2001 pdf download.Bolted Bonnet Steel Gate Valves for Petroleum and Natural Gas lndustries.
5.3.4 Openings
Tapped openings are prohibited unless specified by the purchaser. All openings shall be in accordance with 5.12.
When tapped openings are permitted for testing, they shall not be larger than DN 15.
5.4 Bonnet dimensions
5.4.1 The bonnet stem hole shall be designed to have proper clearance for stem guiding and for the prevention of
packing extrusion.
5.4.2 The bonnet shall include a conical stem backseat in one of the following forms:
— a bushing;
— an integral surface in the case of an austenitic stainless steel valve;
— an austenitic stainless steel or hardface weld deposit with a minimum thickness of 1,6 mm.
5.4.3 The restrictions of 5.3.4 on openings also apply to the bonnet.
5.4.4 Bonnets shall be one piece castings or forgings subject to the same requirements and exceptions as specified in 5.3.1.3.
5.4.5 The gland bolting shall not be anchored to the bonnet or yoke through a fillet welded attachment or stud welded pins. The anchor design shall not include slotted holes or brackets which do not shackle gland bolting during repacking.
5.5 Bonnet-to-body joint
5.5.1 The bonnet-to-body joint shall be a flange and gasket type.
5.5.2 For PN 20 valves, the bonnet-to-body joint shall be one of the following types which are illustrated in figure 5 of ISO 7005-1:1992:
— Type A, flat face;
—Type B, raised face;
—Types C and D, tongue and groove;
— Types E and F, spigot and recess;
—Type J, ring joint.
5.5.3 For valves having nominal pressure greater than PN 20 the bonnet-to-body joint shall be in accordance with
5.5.2, except that the Type A, flat face, joint is not permitted.
5.5.4 The bonnet flange gasket shall be suitable for the temperature range — 29°C to 538°C and shall be one of
the following:
— solid metal, corrugated or flat;
— filled metal jacketed, corrugated or flat;
— metal ring joint;
— spiral wound metal gasket with filler and a centring/compression ring;
— spiral wound metal gasket with filler to be used only in a bonnet-to-body joint design that provides gasket compression control.
For PN 20, the following may also be used:
— flexible graphite sheet reinforced with a stainless steel flat, perforated, tanged or corrugated insert.
5.5.5 Except for all PN 20 valves and all valves in sizes DN 65 and smaller, bonnet-to-body flanges shall be circular.
5.5.6 Bonnet and body flange nut bearing surfaces shall be parallel to the flange face within ±10. Spot facing or backfacing required to meet the parallelism requirement shall be in accordance with either ASME B16.5 or ISO 7005-1.
5.5.7 The bonnet-to-body joint shall be secured by a minimum of four through-type stud bolts. The minimum stud bolt size, for each valve size, in accordance with its PN or Class designation, shall be as follows:
— M10 or 3/8 when 25 DN 65;
— M12 or 1/2 when 80 DN 200;
— M16 or 5/8 when 250 DN.
5.5.8 Valve bonnet bolting shall, as a minimum, meet the following bolt cross-sectional area requirements.
5.5.9 At assembly, all gasket contact surfaces shall be free of heavy oils, grease and sealing compounds. A light
coating of a lubricant, no heavier than kerosene, may be applied if needed to assist in proper gasket assembly.
5.6 Gate
5.6.1 Gate configurations are categorized as illustrated in Annex B.
5.6.1.1 A one-piece wedge gate, as either a solid or flexible wedge design, shall be furnished unless otherwise specified.
5.6.1.2 A two-piece split wedge gate or parallel seat double disc gate may be furnished when specified. A split wedge gate consists of two independent seating parts that conform to the body seats when closed. A double disc gate has a spreading mechanism that forces the two parallel discs to the body seats when closed.
5.6.2 Except for a double disc gate, in the open position, the gate shall completely clear the valve seat openings.
5.6.3 Gates shall be designed so that all parts can function properly independent of the installed valve orientation.
5.6.4 Guides shall be provided in the gate and the shell and shall be designed so as to minimize seat wear and maintain gate to stem alignment in all valve orientations. Gate-to-shell design shall consider wear that may be caused by corrosion, erosion and abrasion.
5.6.5 Gate seating surfaces shall be integral or faced with weld metal. Unless specified, hard faced seating surfaces are not required. Finished thickness of any facing material shall be not less than 1 ,6 mm.
5.6.6 Wedge gates shall be designed to account for seat wear. The dimensions that fix the position of the gate seats relative to the body seats shall be such that the gate, starting from the time of manufacture, can move into the seats, as a result of seat wear, a distance defined as wear travel. The required minimum wear travel varies with valve size, as given in table 5.