Tech Talk - Valve World Americas

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Tech Talk. Valve World Americas - June 2015. It's no longer “Just a bracket…” The Mounting Kit .... For more infor
Tech Talk It’s no longer “Just a bracket…” The Mounting Kit Paradigm Shift in Industry Following the launch in 2011 of the international standard ISO-12490: Petroleum and natural gas industries - Mechanical integrity and sizing of actuators and mounting kits for pipeline valves, 2012 saw the API release of specification API-6DX: Standard for Actuator Sizing and Mounting Kits for Pipeline Valves. API 6DX and ISO 12490 are identical and together are referred to as ANSI/API 6DX-201/ISO 12490-2011. By Tony Lambert - VP of Engineered Valve Automation Hardware, VanAire Inc The scope, as identified within this new specification states that “This international standard defines the requirements for mechanical integrity and sizing of actuators used on valves manufactured under ISO 14313 and API Specification 6D. This international standard is applicable to all types of electric, pneumatic, and hydraulic actuators, inclusive of mounting kit, installed on pipeline valves.” This article is intended to create awareness of this new standard as well as the true importance of the underappreciated mounting kit. All too often, the mounting kit provision is considered trivial, an afterthought deemed a commodity within all the other ‘specified’ control components that comprise a complete automated valve package. There are hundreds of pages of endorsed industry specifications on the requirements of the individual valve, actuator and controls, but very few have been dedicated to the design of the entire package including the details of the mounting kit.

Inadequate mounting kit designs can be a primary reason valves fail prematurely or automation packages fail to function properly and as a result, Industry takes formal steps to ensure safety, quality, consistency and increased up-time in regards to valves and actuators. Finally, the importance of the design, integrity, functionality and quality of the complete assembly is being recognized. Valve manufacturers, actuator companies, distributors and end users are following suit by adopting or referencing this standard which is resulting in a major shift throughout the entire Valve Automation Industry.

Coupling: Driven component (drive adaptor, drive tube, drive shaft) that allows transmission of torque and/or thrust from an actuator driving component to the valve shaft/stem. (4.7) Intermediate Support: Mechanical component (bracket, spool, adaptor flange) that allows the attachment between a valve and actuator. (4.10)

To understand the phrase ‘inclusive of mounting kit’, found within the scope, several key terms need to be understood as defined in the specification:

Mounting kit: Components that may be comprised of combinations of the following: intermediate support, coupling, drive key(s), dowel pin and bolting. (4.13)

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Torque/thrust, maximum: highest torque/thrust of an actuator at specified voltage/pressure with torque/thrust-limiting or pressure-reducing protection devices active, which is used for the design of the mounting kit (4.32)

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Maximum Allowable Stem Torque/Thrust (MAST): maximum torque/thrust that it is permissible to apply to the valve drive train without risk of damage, as defined by the valve manufacturer/supplier (4.12)

Actuator: Electrically, pneumatically or hydraulically powered device bolted or otherwise attached to the valve for the purpose of applying torque or thrust to open and close a valve. (4.1)

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These standards also require sufficient factors of safety exist when calculating the integrity of the mounting kit at 1.1 times the maximum torque/thrust. Section 7.6.1 specifically talks about tensile, shear, torsion and bearing stresses and where applicable welding strength.

The actuator is a driving factor behind ensuring the design integrity of the mounting kit. One must ensure the mounting kit and the valve adequately handles all forces that can be applied. Section 7.6.1 states that the mounting kit shall be designed to transfer all of the loads from the actuator to the valve and to react to them, including loads of 1.1 or more times the maximum torque/thrust output, and it shall take into account the following: •





torque/thrust generated at maximum operating pressure or as limited by relief valve or other pressure-limiting device, for pneumatic/hydraulic actuators; torque/thrust generated by maximum compressed spring force, for spring return actuators; torque/thrust at stall condition or 100 % torque/thrust switch setting, for electric actuators.

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Tensile stresses in mounting kit components shall not exceed 67 % of SMYS when delivering 1.1 or more times the maximum torque/thrust output. Shear, torsion and bearing stresses shall not exceed the limits specified in ASME BPVC Section VIII:2004, Division 2, Part AD-132, except that design stress intensity values, Sm, shall be 67 % of SMYS. •



For all mounting kits, attention shall be paid to deflection and strain. Adherence to these allowable stress limits alone might not result in a functionally acceptable design for the actuated valve assembly. (7.6.2)

Fillet Welds are designed with Strength Efficiency Factor (SEF) of 0.75 or better.

Although the actuator may be the driving factor in a mounting kit design, one must not ignore valve details. Section 8.1.1 states that the purchaser shall ensure that when purchasing an actuator for a valve, the MAST and maximum torque/thrust are compared to ensure compatibility of design and that it is imperative that information described below is exchanged, to ensure that the necessary entities provide and receive the required information for the supply of an actuator, mounting kit or actuated valve assembly. Listed below are some of the criteria found in Sections 8.1 and 8.2: • • • •

Valve Torque and/or thrust data Mast Safety factor and operating time Valve dimensions

Per the ISO definition, there are several components that comprise a mounting kit. Each of these individual components must be

Tech Talk examined closely to ensure that it adequately handles the applied forces. (e.g., It doesn’t matter what type of material is used in the bracket, if the welding isn’t sufficient. or it doesn’t matter how rugged the bracket is if the bolting isn’t strong enough). ANSI/API 6DX201/ISO 12490-2011 addresses some of these concerns by stating the following: •

 elding, including repair welding, of W structural welds, including mounting kit, shall be performed in accordance with procedures qualified to ANSI/AWS D1.1/ D1.1M or an equivalent standard. Welders and welding operators shall be qualified in accordance with ANSI/AWS D1.1/D1.1M or an equivalent standard. (11.2) •



Alternatively, structural welding, WPS, and PQR in accordance with procedures qualified to ISO 15607, ISO 15609 (all parts), ISO 15614-1 or ASME BPVC Section IX and welders and welding operators qualified in accordance with ISO 9606-1, ASME BPVC Section IX or EN 287-1 are acceptable. (11.2) Visual inspection of welds shall be in accordance with ANSI/AWS D1.1/ D.1.1M or an equivalent standard. Parts shall be subjected to a visual inspection in accordance with the manufacturer’s quality procedures. (12.1.3)



Fasteners: •

Bolting in mounting kits shall not be subjected to shear forces, unless otherwise agreed. (7.6.2) • Bolted Joint Slip Calculations are the best way to ensure that the clamping force generates enough friction force to withstand the shear force generated by the maximum torque of the actuator. Adequate friction force will prevent the bolts from going into a shear loading condition.

ISO and API also provide other general requirements and guidelines for mounting kits, such as: •

The mounting kit design and manufacturing tolerance shall ensure the following: • • •



parallelism of the intermediate support mounting faces; concentricity of the PCD of the bolting of the intermediate support; Alignment of the PCD, valve stem, coupling and the actuator drive. (7.6.2)

The mounting kit design shall also consider the following: •



installed orientation of the valve and actuator;

• • •



NOTE Valves installed with horizontal stems can require additional support, e.g. spigots, to ensure accurate alignment of valve and actuator during removal and refitting in field service.

external loading from environmental effects (e.g. wind, snow, seismic activity); blast loading, if specified; frequency of cycling and speed of operation. (7.6.3)

Specifications for metallic mechanically loaded parts and components of mounting kits shall be issued by the manufacturer and shall include, as a minimum, the following:

• mechanical properties; • Charpy impacts, if applicable; • type of inspection document in accordance with EN 10204. (10.6) This article highlighted a portion of the requirements found in ANSI/API 6DX-201/ISO 12490-2011. To obtain the full version of these standards, please purchase or download online. These standards were put into place to ensure integrity of the entire valve assembly package, including the mounting kit. Next time when selecting a valve assembly package, verify that each and every component is adequate to prevent the ‘weakest link in a chain’ from becoming more than just a cute saying.

About the Author Tony Lambert has been with VanAire since January 1996 and currently holds the position of Vice President of Engineered Valve Automation Hardware. Tony has an Associates Degree for CAD and an Associates Degree in Machine Tool Technology from Bay College.

Cited References and Key Sections: ANSI/API 6DX-201/ISO 12490-2011: Mechanical integrity and sizing of actuators and mounting kits for pipeline valves Section 7: Design Section 8: Sizing Section 9: Instrumentation/Regulation Section 10: Materials Section 11: Welding Section 12: Quality Control Section 13: Testing Section 14: Surface Protection

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