API SPEC 6DSS:2009 pdf download

API SPEC 6DSS:2009 pdf download.Specification for Subsea Pipeline Valves.
6 Valve types and configurations
6.1 Valve types
6.1.1 Gate valves
Typical configurations for gate valves with flanged and welding ends are shown, for illustration purposes only, in Figures 1 and 2.
Gate valves shall have an obturator that moves in a plane perpendicular to the direction of flow.
6.1.2 Plug valves
Typical configurations for plug valves with flanged and welding ends are shown, for illustration purposes only, in Figure 3.
Plug valves shall have a cylindrical or conical obturator that rotates about an axis perpendicular to the direction of flow.
6.1.3 Ball valves
Typical configurations for ball valves with flanged or welding ends are shown, for illustration purposes only, in Figures 4, 5 and 6.
Ball valves shall have a spherical obturator that rotates on an axis perpendicular to the direction of flow.
6.1.4 Check valves
Typical configurations for check valves are shown, for illustration purposes only, in Figures 7 to 13. Check valves can also be of the wafer, axial-flow and lift type.
Check valves shall have an obturator that responds automatically to prevent flow in one direction.
6.2 Valve configurations
6.2.1 Full-opening valves
Full-opening flanged-end valves shall be unobstructed in the fully opened position and have an internal bore as specified in Table 1. There is no restriction on the upper limit of valve bore sizes.
Full-opening through-conduit valves shall have a circular bore in the obturator that allows a sphere to pass with a nominal size not less than that specified in Table 1.
Welding-end valves can require a smaller bore at the welding end to mate with the pipe.
Valves with a non-circular opening through the obturator shall not be considered full opening.
6.2.2 Reduced-opening valves
Reduced-opening valves with a circular opening through the obturator shall be supplied with a minimum bore as follows, unless otherwise specified:
valves DN 300 (NPS 12) and below: one size below nominal size of valve with bore according to Table 1;
— valves DN 350 (NPS 14) to DN 600 (NPS 24): two sizes below nominal size of valve with bore according to Table 1;
— valves above DN 600 (NPS 24): by agreement.
EXAMPLE A DN 400 (NPS 16) — PN 250 (Class 1500) reduced-opening ball valve has a minimum bore of 287 mm.
— close to open, with MPD on both sides of the obturator and with the valve cavity at atmospheric pressure; open to close, with the MPD in the valve bore and the valve cavity at atmospheric pressure.
7.20.2 Allowable stresses
Tensile stresses in drive-train components, including stem extensions, shall not exceed 67 % of SMYS when delivering the design thrust or torque. Shear, torsion and bearing stresses shall not exceed the limits specified in ASME BPVC, Section VIII, Division 2:2004, Part AD-132, except that design stress intensity values, Sm, shall be 67 % of SMYS.
These stress limits do not apply to the components of rolling-element or other proprietary bearings or high bearing-strength-capable materials that are included in the drive train where manufacturer’s recommendations or limits derived from tests and service experience apply. These limits shall be justified in design documents.
The drive train shall be designed such that the weakest component is outside the pressure boundary.
A strength efficiency factor of 0,75 shall be used for fillet welds.
7.20.3 Drive train bolting
Bolting in the drive train shall be designed to accommodate the direct loading applied by the full
actuator/gearbox output and, if applicable, loads from pressure. Bolting shall not be subjected to direct shear.
7.21 Stem retention
Valves shall be designed to ensure that the stem does not eject under any internal pressure condition or if the packing gland components and/or valve operator mounting components are removed.
7.22 Stem/shaft protector
If specified by the purchaser, the design shall have provisions for fitting a stem/shaft protector or cap. If the protector or cap can contain pressure, the protector or cap and method of attachment shall be capable of withstanding the valve design pressure and external hydrostatic pressure and shall be hydrostatically tested in accordance with this International Standard. The protector or cap shall have provisions for venting prior to removal and during fitting.
7.23 Hydraulic lock
If valves or valve components are designed for subsea maintenance, provisions shall be made for venting of all enclosed cavities to ensure that entrapped fluid does not prevent the disassembly, or subsequent reassembly of the components.