1. purpose
1.1 This global specification defines the handling and weather protection requirements of cold box control valves, with bellows seals, manufactured by Samson Controls. It is important for the construction supervisor to follow this specification to ensure that rainwater does not enter into the valve extension. Water egress can damage the valve and/or cause the valve to malfunction when the plant is cooled down and the trapped water turns to ice.
2. scope
2.1 This specification applies to all equipment, cold boxes, pump boxes, skids and fabricated systems in which Samson, bellows sealed, cryogenic control valves are installed. It applies to fabrication work done by Air Products or third party fabricators doing work on Air Products’ behalf.
2.2 This document does not apply to Samson valves constructed without bellows type stem seals used in cryogenic systems.
3. Related documents
3.1 Air Products Engineering Documents 4WPS-VALV12 Use of Samson Shipping Covers for Pressure Testing of Cold Box Process Piping and Valve Weather Protection
3.2 Samson Documents EB 8093 EN Mounting and Operating Instructions
3.3 Samson Contact Information SAMSON Controls, Inc. SAMSON Controls AG 4111 Cedar Boulevard Weismullerstrabe 3 Baytown, TX 77520-8588 D-60314 (281) 383-3677 Frankfurt am Main www.samson@samson-usa.com Germany 10 1901 011 49 694 009 www.samson.de
4. Definitions
4.1 Bellows Seal. The bellows seal isolates the process fluids in the valve body from the upper portion of the cryogenic extension. This seal limits the migration of cryogenic fluids to the lower portion of the extension and reduces icing of the bonnet flange and packing area. This is accomplished by welding one end of the bellows to the valve plug and mechanically sealing the other end to the inside of the valve extension tube.
5. REQUIREMENTS
5.1 Samson cryogenic valves installed in cold boxes are, in most cases, shipped to the site without actuators. This reduces the shipping envelope of the cold box. The actuators are shipped separately along with the cold box to site. Positioners, solenoids, and air sets included with actuator assemblies are shipped mounted and piped to the actuators.
5.2 The cryogenic valves can be shipped either with or without the yoke assembly. When shipped with the yoke assembly, it is wrapped with heavy plastic and securely fastened to prevent moisture egress into the upper extension area of the valve during storage and transit. The upper extension area contains a bellows which, if not properly protected, could trap moisture that would freeze, preventing the valve from operating when the valve is placed in cryogenic service. The plastic is not to be removed until the actuator is mounted to the valve.
5.3 Cryogenic valves shipped without yokes have plastic caps installed in the shipping cover to prevent rainwater and debris from entering the upper valve extension during shipment and cold box construction/erection. Heavy plastic shall also be used as further protection against water egress into the upper bonnet section. The plastic shall be secured for transit and not be removed until the yoke and actuators are fitted at the plant site. In addition, they are shipped without the upper plug stem extension. This upper plug stem extension is removed by the cold box fabricator and shipped separately. Further information pertaining to shipping covers can be found in 4WPS‑VALV12.
5.4 Cryogenic valves shipped with yokes installed already have the upper plug stem extension and packing assembly installed. The packing assembly will prevent rainwater and debris from entering the upper valve extension when properly tightened. Before the valve and yoke assembly are wrapped with plastic, the threaded bushing or packing nut is fully seated, which applies the appropriate packing load to the stem.
5.5 Note: For cold boxes shipped before September 2002, special Samson anti-rotation tools are required to assemble the upper plug stem to the cryogenic valves. These tools must be used to prevent the twisting of the lower valve stem and bellows during the installation process. Otherwise, the bellows could be damaged.
5.5.1 Cold boxes shipped to site after September 2002 may have valves that were redesigned such that the anti-rotation tools are not required. This may be verified with Samson or with the specifying engineer.
5.6 Yoke and Actuator Installation
5.6.1 Obtain and review the Samson “Mounting and Operating Instructions” manual EB 8093 EN.
5.6.2 Locate or obtain the special anti-rotation Samson tools. (Not required for cold box valves shipped after September 2002.)
5.6.3 Remove the plastic from the valve assembly.
5.6.4 Install the upper valve stem extension and yoke according to Section 6, titled “Assembly,” page 13 of manual EB 8093 EN.
5.6.5 Install the actuator to the yoke according to Chapter 2, titled “Assembling and Adjusting the Valve and Actuator,” page 6 of manual EB 8093 EN.
5.6.6 Connect the instrument air and electrical wiring according to the construction drawings.
5.7 Actuator Installation
5.7.1 Obtain and review the Samson “Mounting and Operating Instructions” manual EB 8093 EN.
5.7.2 Locate or obtain the special anti-rotation Samson tools. (Not required for cold box valves shipped after September 2002.)
5.7.3 Remove the plastic from the valve and yoke assembly.
5.7.4 Install the actuator to the yoke according to Chapter 2, titled “Assembling and Adjusting the Valve and Actuator,” page 6 of manual EB 8093 EN.
5.7.5 Connect the instrument air and electrical wiring according to the construction drawings.