The manufacturer shall determine the need for and verify suitability of lifting points of the valve。 The purchaser shall specify when lifting points on the valve are not required。

If the valve manufacturer is responsible for the supply of the valve and operator assembly, the valve manufacturer shall verify the suitability of the lifting points for the complete valve and operator assembly。

NOTE Regulatory requirements can specify special design, manufacturing, and certification of lifting points。

4。19Drive Trains

4。19。1Design Thrust or Torque

The design thrust or torque for all drive train calculations shall be at least two times the breakaway thrust or torque。

4。19。2Allowable Stresses

Design stresses for tensile stress, shear stress (including torsional shear stress) and bearing stress shall comply with ASME BPVC, Section VIII except that the design stress intensity value, Sm, shall be taken as 67 % of SMYS。

In addition the average primary shear stress across a section loaded under design conditions in pure shear, e。g。 keys, shear rings, screw threads, etc。, shall be limited to 0。6 Sm。

The maximum primary shear under design conditions, exclusive of stress concentration at the periphery of a solid circular section in torsion, shall be limited to 0。8 Sm。

NOTE Allowable values of bearing stress can be found in the general notes section of ASME BPVC, Section II, Part D。

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。

4。19。3Allowable 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。

4。20Stem 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。

4。21Fire Type-testing

Fire type-testing certification of the design may be provided。 When required, the fire type-testing shall be performed in accordance with O。5。

4。22Antistatic Device

Soft-seated ball, plug, and gate valves shall have an antistatic device。 Testing of this device shall be in accordance with H。5 if specified by the purchaser。

5Materials

5。1Material Specification

Specifications for metallic pressure-containing and pressure-controlling parts shall be issued by the manufacturer and shall address the following:

—material grade;

—chemical analysis;

—heat treatment;

—mechanical properties (tensile);

—certification to report all items listed in 6。1。

Other requirements of the material specifications shall be as follows, if applicable:

—carbon equivalent (CE);

—Charpy impacts;

—hardness;

—testing。

Metallic pressure-containing parts shall be made of materials consistent with the pressure–temperature rating as determined in accordance with