API RP 945:2003(2008) pdf download
API RP 945:2003(2008) pdf download.Avoiding Environmental Cracking in Amine Units.
6.2.3 Relnspection of Undamaged Equipment
Reinspection should he conducted at appropriate intervals on any of the equipment listed in 63 that has been found to he undamaged during presiow. inspection. The intervals can he set by experience, equipment criticality, and whether or not the equipment has received PWHT Reinspection should include the examination of randomly selected areas. Reinspection intervals should he reevaluated if significant process changes occur, such as amine type. amine solution composi(ion, flow rate increases and!or temperature increases.
6.3 EQUIPMENT AND PIPING THAT SHOULD BE INSPECTED
6.3.1 Equipment
Common equipment that should be considered for inspection includes: absorbers. accumulators. coalescent columns, condensers, coolers, contactors, extractors, filter vessels, flash drums, heat eschanger shellslchannels/tuhe bundles, knock- out chums, reactivaton, reboilers, reclaimers, regenerators. scrubbers. separators, settlers, skimmers, sour gas drums, stills, strippers, surge tanks, treating towers, and treated fuel gas drums.
Inspection of welded pressure-containing equipment associated with air coolers, such as header hoses, should be con sidered. Pump cases in amine service that have had weld repair’ should he inspected for the presence of cracks.
Specific areas for inspection include those in and adjacent to longitudinal and cireumferential welds: manway and nozzle attachment welds (including welds that attach reinforcing pads): attachment welds of internals (tray and downcomer welds, support attachment welds for distributors and vortex elinsinatorst areas repaired by welding: heat-affected zones on internal surfaces opposite externally attached structural steel platforms. ladders, and the like: and arc strikes, The weld areas behind, or associated with, leaking panels of alloy strip-lined vessels should also he inspected.
Cracks and related defects initiate internally. Therefore, the primary inspection effort should he directed toward internal surfaces contacted by amine solutions.
6-3.2 Piping
All process piping associated with amine units that have not been postweld heat treated should be considered for inspection to detect cracking. It might be mote economical to replace small diameter piping than it is to inspect it, and this alternative should he evaluated. Spccihc areas to be inspected include those in and adjacent to the following locations:
a. lds of pre.sure.contaIning piping.
b. Attachment welds associated with pipe ‘.hucs. support clips, or other non-pressure-containing attachments.
c. Weld arc strikes found on pipes.
d Attachment welds of reinforcing pads for nozzles.
e. Repair welds of any type.
Stress corrosion cracks and related defects initiate internally. Thcrciorc. the inspection should be directed toward internal surfaces that are contacted by amine solulions,
The folki%s in luLihod’. ar-c useful for the estcrnal nondeslructñe inspection ol piping:
a. Ultrasonic testing tscc 6.4.3).
b. Radiographic teMing see 6.44).
c. Visual eswrnnahon (see 6.4.6).
At times, it may be appropriate to remove selected pipe segments. cut them in half longitudinally. arid use WFMT to inspc’..l their internal surfaces.
6.4 EXAMINATION PROCEDURES AND METHODS
6.4.1 Wet Fluorescent Magnetic Particle TestIng
et fluoicscci IkiactI particle tc.’.tin (WFMT) ‘.
sr,i)- sensitive method fiji detecting surface-connecLed cracks and discontinuities. WI-MT using an A(’ yoke is one of the primary nicthods ft’cornmcnded for internal inspection of pressure vessels in amine service.
Two modes o(operrdron arc asailable for the magneti/ing – AC yoke and half-wave DC prods. The AC vike n’iodc achieves greater sensitivity in locating surface defects, and also reduces the effects of background interference. U these reasons, it is the recommended mode. The half-wave IX’ mode offers improved penetration of the magnetic field into the area that is being inspected, thereby permitting the detection of near surface defects in addition to surface defects. Ilosseser. use of DC prods is not recommended because they can induce arc burns that could initiate future cracking.
