API SPEC 6D:2008 pdf download

API SPEC 6D:2008 pdf download.Specification for Pipeline Valves.
7.17 Travel stops
Travel stops shall be provided on the valve and/or operator and they shall locate the position of the obturator
in the open and closed position. The travel stops shall not affect the seang capability of the Valve. 7.18 Actuator, operators and stem extensions
7.18.1 General
Actuators can be powered by electric, hydraulic or pneumatic means. The output of the actuator shall not exceed the stress limits of the valve drive train permitted by 7.20.2. unless othorwse agreed.
NOTE Typical quarter-turn valve-to-actuator interfaces are given in ISO 5211 l.
7.18.2 MisalIgnment
Misalignment ci- improper assembly of components shall be prevented by suitable means, such as a dowel pin or fitting bolt, which ensures the correct location of manual or powered operators and stem extension assemblies.
7.18.3 Sealing
Operators, stem extensions and their interfaces shall be sealed to prevent ingress of external contaminants
and moisture.
7.18.4 Overpressure protection
Operators and stem extension assemblies shall be provided with a means of preventing pressure build-up in the mechanism resulting from stem or bonnet seal leakage.
7.18.5 Protection of extended stems and shafts In below ground service
Extended stems and shafts in below-ground servce shall be protected by an extension casing (housing).
7.19 Ufting
Valves of size DN 200 (NPS 8) and larger shall be provided with lifting points, unless otherwise agreed. The manufacturer shall verify suitability of the lifting points. If the valve manufacturer is responsible for the supply of the valve and operator assembly, the valve manufacturer shall venly the suitability of the lifting points for the complete valve and operator assembly.
If the purchaser is responsible for the supply of the operator assembly, the purchaser shall provide adequate information to enable the manufacturer to verify the suitability of the lifting points for the complete assembly.
NOTE Regulatory requirements can specify special design, manufacturing and certification of lilting points.
7.20 Drive trains
7.20.1 Design thrust or torque
The design thrust or torque for all drive train calculations shall be at least two times the breakaway thrust or torque.
NOTE This design factor is to allow for ffirust or torque increase In service due to Infrequent cycling, low-temperaIe operation and the adverse effect 01 debris.
7.20.2 Allowable stresses
Tensile stresses in drive train components, induding 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 Code Section VIII, Division 2, Part AD-132, except that design stress intensity values, Sm. Shall be 67 %0ISMYS.
These stress limits do not apply to the components of roll.ng.elenient or other propnetary bearings or high bearing strength capable materials that are included in the drive train where manufacturers 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 br fillet welds.
WARNING — If an actuator or operator c-an deliver a thrust or torque that Is greater than the design thrust or torque of the drive train, such a thrust or torque can result in permanent deformation or failure of drive train components.
7.20,3 Allowable deflections
Deflections of the extended drive train Shall not prevent the obturator from reaching the fully closed or fully open position.
For all valves, attention shall be paid to deflection and strain. Adherence to the allowable stress limits of design codes alone might not result in a functionally acceptable design. The manufacturer shall demonstrate. by calculation or test. that under loads resulting from design pressure and any defined pipe or external loads, distortion of the obturator or seat does not impair functionality or sealing.
7.21 Stem retention
Valves shall be designed to ensure that the stem does not eject under any internal pressure condition Ot it the
packing gland components andior valve operator mounting components are removed.
7.22 Fire type-testing
If specified by the purchaser, fire type-testing certification of the design shall be provided. Fie type-testing shall be carned out in accordance with Clause 0.5, unless otherwise agreed.
7.23 Anti-static device
Soft-seated valves shall have an anti-static device, unless otherwise agreed. If specified by the purchaser.
valves shall be tested in accordance with Clause B.5.
7.24 Design documents
The design shall be documented in a retrievable and reproducible form.