Chemical Processing - July 2008 - (Page 43)

PLANT INSITES aware that internal restrictions inside the equipment may set maximum ﬁll or drain rates. For instance, bubble-cap or valve trays inside towers may limit draining rates. • Assess water quality against the vessel’s material of construction. e prime example of what to watch for is chloride content of the water if you are dealing with stainless steel equipment or piping. • Make sure that connected piping systems that aren’t isolated during pressure testing can deal with the test pressure. • Thoroughly go over testing procedures in suitable management of change, process safety management, and hazard and operability reviews. • Keep personnel away from areas where pressure testing is taking place. e tower in Figure 1 poses ﬁve potential trouble spots for a hydrostatic pressure test: two sections of valve trays, two sections with internal partitions creat- ing potential dead spots, as well as the extra 56 psi of static pressure on the bottom. Restricting ﬁll and drain rates to appropriate values will prevent damage to the valve trays. e dead spots require either internal venting or external venting through nozzles to prevent the relatively weak internals from bearing excessive load (when ﬁlling) or having a partial vacuum pulled (when draining). It’s crucial to account for the static head from the vessel height in setting MAWP and test pressures. The vessel was successfully pressure tested with all internals in place by taking all factors into account and allowing for them. Water is a safe, reliable medium for pressure testing. However, like all other plant work, such testing takes planning and thought to correctly design the equipment and piping. BY ANDREW SLOLEY, contributing editor ASloley@putman.net www.cashco com Innovative Solutions Universal Control V alve When quality counts choose Cashco. For 85 years, the industry has turned to Cashco for precision control solutions. The Ranger QCT is a universal control valve. It offers versatility, adaptability and ease of maintenance in almost any application. The Ranger is designed for use in steam, chemical, gas and cryogenic liquid applications. solutions for virtually any project. surpassed only by the service and support. Centers with factory-trained specialists. Don’t wait any longer to partner with the industry’s leader in process control. Call us today at 785-472-4461 for immediate assistance and technical support. VAPOR CONTROL SYSTEMS Valve Concepts, Inc. SYSTEMS TEMS Cashco, Inc. • P .O. Box 6 • Ellsworth, KS 67439-0006 Ph. (785) 472-4461 • Fax: (785) 472-3539 www.cashco.com http://www.westernstates.com http://www.cashco.com http://www.cashco.com http://www.cashco.com http://www.westernstates.com

Table of Contents Feed for the Digital Edition of Chemical Processing - July 2008

Chemical Processing - July 2008 Contents From the Editor ChemicalProcessing.com Field Notes In Process Energy Saver Compliance Advisor Who’s a Big Hit? Succeed with Condensate Control Take Some Basic Steps with pH Measurements Steam Projects Provide Fast Payback Process Puzzler Plant InSites Equipment & Services Product Spotlight/Classifieds/Ad-Lits Ad Index End Point

Chemical Processing - July 2008

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