Wow,
Thanks to you all for your responses. We are not new to this business and actually re-tubed this identical unit in 1997 and many more since 1980. This unit, like almost all of the condensers and HEX we have re-tubed have following OEM designs. This change is something new here in Alaska. I...
Our customer has asked us to re-tube their GE steam turbine condenser, replacing the original 2134 1" OD x .049" (18 BWG) Admiralty D Brass tubes with 1" OD 304 Stainless tubes. There is a section of 304 tubes originally installed as a separate cooling section in this unit that uses 1" OD x...
We are designing 2 seperate Section VIII-1 DA tanks. The 1st is horizontal at 8'6" OD x 24' with F&D heads. The 2nd is vertical at 8'0" OD x 16'4" with F&D heads. All shell and head material is 1/2" SA 516-70 and is exempt from CVN testing per UG-20(f), UCS Curve B.
Our calculations show fiber...
A client has a question I cannot answer. Not a big surprise there. A 1950's era Wickes coal fired 475# MAWP power boiler has five PRV's. This typical 1 of 6 is on a US Army Base in Alaska. One on the SPHT at 475# is normal. The remaining are located across the top of the Steam Drum. These are...
Height vs diameter has a significant factor for wind and seimic loads. We have found foundation cost, available space and steel prices drives the design. Often larger steel plates while reducing welding adds extra handling, larger cranes etc. Our experience in Alaska is that any tank with the...
I think Tc7 may mis-understand the role of the A-I. We contract the service of a large firm that provides us with A-I's. These professionals are trained to interpret the NBIC and provide a review inspector for documents prepared by the Code shop performing the work. The A-I does not design the...
The legality of use is clearly determined by the local pressure vessel jurisdiction (if any the vessel is operated in. Local laws and conformance to to applicable Codes can be confirmed by your local State Boiler Inspector or your equipment insurer. The plate repairs using flush inserts are...
Thank you again saplanti. I errored in omitting that the range of tubes we work with included SS and CS in many sizes. We do often purchase the material from the mill and apply actual dimensions to our calculations. Your reference is new to me. Could you send the section 19.2.2 boilers. I am...
Thank saplanti for your research. We have used these formuli and our own version on 10's of thousands of tube joints from 3/8" copper thru 4" x .220" WT at operating pressure in the thousands of PSI. The tube hole serations in HEX and drums resist axial expansion that tends to rip, the tubes...
I am sure I read a requirement for qualified expanding procedures recently. I cannot relocate what I saw. I have studied expanding principals written by the USN from prior to WWII. Unlike Welding Procedures (WPS) the Codes have not required "Expandinng procedures. Is this about to change?
ASME Sections I, IV and VIII-1 all have brief specifications for tube expanding. Common is the 1/32" clearance between tube OD and tube-hole ID (see HG 360.2). This is the common .031" clearance we see in new construction. Rarely, during a repair do we find this hole size on firetube boilers...
We will MT the weld. We are considering welding a repad of the same material as the annular ring prior to the attachment. Is the material suitablity of attachments to the annular plate or other primary plates addressed in API 650. If not what practical guidance would be followed?
Our experience is that the difficulties with the "breakdowns" on 3/8" floors is minor compared to greatly reduced time for lap fitup and welding. I would think 3/8" is the practical limit.
In an 80 ft. diam tank we are installing a heating coil. Can a standoff be welded with fillet welds to the A516-70 annular plate, without performing MT. What NDE would be required? The plate stands will be 4" from the shell (beyond the critical zone). The tank is designed for minus 60 deg. F but...
The design for a 102 foot diam. open top tank with fltg roof does not require an annular plate. Due to construction of a new concrete foundation, an annular ring type design of A 516-70 is used to allow use of A 36 floor plates. The junctions of the annular ring will be a combination of single...
Does API 650 and 653 allow a qualified tank engineer to design a weld joint on a new replacement floor closer than 12" from the shell, per Par 5.1.5.4? ASME allows some engineering design changes if properly supported, Does API?.
Thanks for the response. The intent was more than to seal the joint. I found no similar reference in Sec 1, VIII or NBIC. Also B31.1 or B31.3 would not be a stretch for this application. Our advice to our client will be to replace the coupling/nozzle or live with the threaded joint
A customer has requested the welding of a 3/4" threaded nipple into an SA 105 Sec. VIII-1 coupling nozzle. I seem to remember a Code provision that allowed this if all of exposed threads were "consumed" in the fillet weld. Where might I find this provision.
The welding of tube ends to plugs should be a last resort. At best the plug should be welded to the protruding end of the tube only. This will provide a small flexible joint. If the tube is then also welded to the vessel wall (usually a thick section) then you have created a higher restrained...
