Thanks for the correction ak762. I am thinking of 2.7-3 which allows fillet welds in shear if I read correctly. If you can't modify the design but need to meet the dnv then your a bit stuck. I still don't know the code you need to meet or the eye design but I was speculating that you could...
The responses are getting a little confusing. Duplex steels solidify as 100℅ferrite the transform partially to austenite on cooling based on two things. 1- cooling rate and 2- proportion of austenite forming elements. If your ferrite is too low you either need to reduce Ni or N etc or increase...
Is this a form of the ferroxyl test used for plating porosity? Its common to use copper sulphate also which will plate out copper as a test for steel or stainless.
Nick
The overmatched chemistry of 2209 is designed to produce 35-65 without any pwht. Its rare to pwht duplex welds in my experience. Maybe the increase in austenite forming elements in the weld metal is promoting transformation more than expected. Its also possible you have Nitrogen pick up if you...
Like Ed said passivate the parts. Or pickle and passivate if its serious contamination. It gets done all of the time either as a clean up or as a precaution. I expect a local plating shop which services the aero or oil industry will be able to process in bulk. After treatment you could prove its...
I think Alok is asking if the fabricator can use a previously qualified wps for the new job. Providing that the fabricator doing the work performed/owned the previous qualification then yes they can user it within the allowable range of their qualification. Note that this assumes you have no...
Everyone is focusing on G48 but that doesn't appear to be your problem. Although I'm supposed that your passing the G48 with a lack of root fusion as I we could expect this to cause a crevice failure. Can you describe the root gap used and backing gas (mix and Max o2 content). Unless you use a...
There is a military spec which I think includes some guidance. I think its ff-s-86. The fastener manufacturers often follow it. Check the sps group website data sheets for socket head caps
A well designed CP system will prevent and galvanic and crevice corrosion in any connected materials. For duplex steels follow DNV-RP-F112 Guidelines and you should be OK. This is a bit of a generalisation but if it weren't close to the truth we would have big issues with all installed subsea...
For long term subsea service you will no doubt have cathodic protection. In this case and due to the function you may have to leave the surfaces bare. As Steve suggests you can consider stainless steels/CRA's if the parts are shielded or isolated from the cp System. Note that bare steel and bare...
The cost of sacrificial anode cp may not be significant. It all depends on the size of the structure you need to protect. If its small and you use the coating you have specified then it may simply be enough to attach one anode. ( obviously you will need to run the calcs to dnv-rp-b401 or...
As good a spec as it is this is one of those occasions when I'm not prepared to trust eemua. There are too many papers and standards that conflict. The words strictly and typically suggest ( of course) that its not always the case.
Thanks for the replies
Nick
5 degree water temperature and fluid temperature. No internal corrosion issue with 316 and we don't need the tensile strength. The only logical reason for choosing 25Cr was for external seawater resistance. I.e. the CP won't throw. Maybe the first post has it that simply its belt and braces...
