I am seeking information on an "Inspection Stratergy" for 10 PSA Adsorbers. Dimensions:- 21'-9" x 6'-6" dia. x 0.94" thk. Material A-516 Gr 70. Service life 10 years. Pressure cycles from o to 300 psig every 8 minutes. Please advise on the current Isepection stratergy in your particular refineries. Thanks Ian.

Where are you located and which codes/standards and regulations apply to you ? For pressure vessels in the USA, I believe that these two documents will goven and guide your inspection program: API 510, Pressure Vessel Inspection Code: Maintenance Inspection, Rating, Repair, and Alteration, Eighth Edition (1997, June 1). API 572, Inspection of Pressure Vessels, First Edition (1992, February). An excellent/informative website is: http://www.osha.gov/SLTC/pressurevessels/ Let us know more about your process........It sounds like you frequent cycling vessels should have been designed to ASME VIII, Division 2 (or the international equivalent)......were they ??? My opinion only... -MJC

Ian Haynes If PSA Adsorbers are designed to ASME Code for this pressure and temperature conditions with A 516 Gr 70, inspection strategy is to inspect each PSA Adsorber in a sequence and planned inspection schedule as follows: 1. Inspect internally - Visual 2. Inspect internal welds - WFMPT - Wet Fluorscent Magnetic Partcile Inspection 3. Inspect internal welds - UT Flaw Check. 4. Pneumatic test of shell to nozzle - reinforced pad welds Cyclic fatigue due to pressure variations - on nozzle welds - for A 516 Gr 70 - even if operated for 20 years (approximates to 1.4 million cycles in 20 years) may not relatively affect the vessel. If with this pressure pulsation (0 to 300 PSIG), it is combined with temperature variations (thermal stress) then possibility of cyclic fatigue affecting the nozzle welds and reinforce pad welds are likely. Pressure pulsations would affect the inside dampeners - if provided - or skirt ring support stiffening ring welds or skirt support areas in PSA Adsorbers. As inspection strategy, you could do thorough inspection starting from the longest and oldest operated vessel which had seen the maximum cycling and then inspect in a planned sequence all your 10 PSA Adsorbers. This will give enough input for future monitoring and also for repair approach Trust this is of help to you C.V.Srinivasan Nishi Engineers Pvt Ltd India Nov 04,2005 E-mail:nishi@vsnl.com >Since the PSA are in cyclic service continuously from low >pressure to high pressure,there is a possibility of cyclic >fatigue cracks in the attachment welds inside the vessel. >Hence ,it is recommended to carry out 100 %WFMPT of >attachment welds/skirt to shell weld and spot radiography of >shell weld joint to identify the crack.Vessel out of >roundness measurement s and peaking/flattening measurements >on weld seams will also helpful to find out deformation . > >regards,