How long can I move my work piece after welding?

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Hi all,I have a few questions on welding, hope I’ll have some help from here.I have 3 rectangular steel blocks each about 17m X 0.4m X 0.2m. They are to be welded at the 0.4m X 0.2m face, forming a straight line. They joints formed between blocks are a narrow gap joint with an 11mm gap. SAW method would be used as the welding method. It would resemble this:__________ __________ __________I would like to know is that, upon completion of welding for these joints, how long must I wait before I can move the entire welded blocks? I understand that to prevent hydrogen cracking, typically 3 days are required for cooling. As these blocks will be on a jig during welding, upon completion of it, I want to free the use of the jig, hence I’m wondering if it is possible if I can move the entire welded block during these 3 days of cooling to some other place and allow the cooling to take place while I can use the jig to perform another set of welding.Also, would the lifting cause any distortion to the straightness of the blocks?I’d really appreciate for any help I can receive from here. Thank you
Reply:Those blocks are HUGE!  What are they being used for?
Reply:Most warpage happens in the cooling phase over a period of time but if these pieces are held in a jig during welding will likely cause internal stresses that can lead to cracking because they are restrained and have no way to expand and contract from the heating and cooling. You may need to monitor preheat and interpass temperatures for such heavy plate. I think if the pieces get down to a temperature where you could quickly touch them (300-400 deg's ?) you'd be OK to move them. You may have to stress relief them which requires even more heat. It would help to know what they are for?
Reply:Hi @shortfuse and @Welder Dave, They're mainly used for support in a vertical position like this: | | |@Welder Dave, with regards to the internal stresses due to it being restrained by the jig, its a valid concern, but in this case, measures have been taken care of that issue. After the welding is completed, a post weld heat treatment would be carried out for an hour at 150 degC. After which, an insulation blanket is used to cover the weld joint, protecting the joint from the outdoors environment. The joint will be covered for about 3 days. Typically, the preheat and interpass temperatures do not exceed 200 degC. @welder Dave, may i know which unit of temperature you are referring to?
Reply:3 days seems like a long time, I would bet you could pull it out of PWHT and set it on some stickers, cover it up with whatever you are going to use and free up the jigExperience is something you get right after you need it
Reply:If you are using SAW and proper preheat/post heat then hydrogen should not be a problem.  Like Welder Dave said once they are cooled down to around 300 it is all over and handling is not going to change what you have.  A post weld treatment at even 150 C would not do anything unless you have created a hydrogen problem by not using a low hydrogen process and needed more time to release hydrogen.  On that thickness it is not going to cool very quickly so remove from fixture once black , wrap up in blankets of kaowool and let it sit.  Insulating the joint would keep it up in the 150 C range for many hours.  I find it odd that your measurements are in metres.  No one in my experience deals with metres... only millimeters.  No confusion.  It sounds like you are splicing flanges for welded beams.  You are not going to cause any bending or distortion when handling hot as long as it is black and you use spreader bars and at least two cranes.
Reply:I was talking Fahrenheit and I don't think 150C is enough heat to remove any stresses. Stress relieving is usually over 1000F. What exactly are making supports for? It's hard to give very specific advice when we're guessing what you're trying to do.
Reply:How are you going to move it?  It's about 150 feet long
Reply:@Welder Dave,These structures are the legs of the jackup rig. As these legs are too long (almost 500ft) to be fabricated at one go, they are split into section lengths (about 150ft per section) Each section is previously joined from smaller lengths of about 50ft and 30ft. So i'm looking into the welding of 3 smaller lengths (2 joints) together. The welded lengths would be about 140ft. The SAW process is a multipass welding process. @lotechman, may i know what you meant by "as long as it is black"?@Rock knocker, gantry cranes or tandem lifting by crawler cranes would be good enough for lifting.
Reply:By "black" he means at black heat.  Hot, but not hot enough to have even a hint of dull red in very low light."USMCPOP" First-born son: KIA  Iraq 1/26/05Syncrowave 250 w/ Coolmate 3Dialarc 250, Idealarc 250SP-175 +Firepower TIG 160S (gave the TA 161 STL to the son)Lincwelder AC180C (1952)Victor & Smith O/A torchesMiller spot welder
Reply:Sub-Arc is a hot fast process. Are there no welding engineers involved in this project? If your sub-arc is all done from one side and the pieces are restrained in a jig to keep them flat, you can be sure there's going to be a lot of built up stress. You'd almost have to fit them in a pre-bent position and they would contract and pull straight while cooling. It's probably not practical but welding from both sides would be another option to lessen built up stresses.
Reply:I would like to see some pictures of this jackup rig and the legs you are welding together in 3 separate sections.... I cant tell you anything by you displaying Lines like

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   or ________  _______ ________Give us some pictures so we can see the joints being formed for legs. I personally have worked on a couple jackup rigs and many many jackup barges and have never seen steel blocks used for legs. They are generally Large O.D. piping with gear teethed siding going all the way from the bottom to the top. There are Large square pads at the bottom for the legs to go into the Sea floor. Your saying 500 FT. legs!? this has to be a very very large jackup. I have only worked on smaller jackups with legs of 90-200 FT. if I recall correctly. I have been on the Seacore Supporter and the Seacore Liberty(Which I think has been sold to somebody else now) both were around 200 ft legs. The smaller 90 ft legged jack ups I worked from were EBI (Elevating Boats Incorporated) Sal Duhe, Donald Olsen and a couple others. What grade steel is this anyways? that could be a major question in welding together blocks like this. SAW may be the way to go. I don't know, I have never used this process. I just cant picture the results or joints to tell you anything honestly. You say this is a jack up rig.... I witnessed probably 3 Hercules jackup Drilling rigs come to our field and they all had "Crane boom" style legs. All piping interweaved with X-supports and Y connections. All utilized gear jacking methods. I want to see some pictures of this jack up rig and the joints you are forming for the leg.Last edited by AndrewDavenport89; 06-01-2015 at 12:16 PM.
Reply:@Welder Dave,yes, we have considered issues on single side welding and we are intending to set the work piece in pre-bent position. Currently the joint is a double v groove, so alternate SMAW can be done@AndrewDavenport89,my bad.. initially i wasn't going to reveal it was for a jackup rig, hence i used the term 'steel blocks'. Attached are a prototypes of the joints mentioned. Top picture is the current weld joint which is a double v joint and the welding process is SMAW.Bottom is the narrow gap v joint which i'm hoping to use SAW process for it. Attached ImagesLast edited by martianoo; 06-02-2015 at 03:58 AM.
Reply:Those are the teethed gears for the jackup system correct. From the prototype that is what they look like. We had to repair them before. They are sleeved inside the piping. Definitely SMAW, (6010 root)7018 or 8018 the rest of the way out. Preheat and PWHT. What grade steel is that? If you have any knowledge on code work AWS D1.1 there are different preheat and post heat temps for different grade steels. Depending on your heat number and grade it will tell you. If you can not find the info call your Mill that sent you these. Oh and BTW Double V-Groove is the way to go in my honest opinion. Have them weld the root and hot pass for one side, Backgouge into the root pass from the other side and weld root and hot pass as well. This way you have full penetration off the bat. Then he can swap sides welding a couple passes then go to the other weld a few. You have to distribute the heat in order for it not to warp the intended area. I don't think you have to actually worry about how long you should wait until you move it. General rule of thumb weld it, then PWHT (IF CALLED FOR)! Then when it comes to ambient temperature and you can touch it in a couple hours. Its time to move it around. I hope this information I have told how helps in any way. I can not actually give you a Welding Procedure Specification like this. I am not a Senior CWI only a CWI so I can not write this. If I were you I would take my steel grade, Heat number, Prototype to a Weld Testing company. A SCWI can write you a WPS on this process. Where are you located? I have a weld testing company that can probably help you out with a procedure. You may need a PQR done before you start this.I know you want to use Sub-Arc because its hot and fast. Not necessarily the best solution. A lot of companies use SAW because it lessens the fab time, but if you do not have a qualified operator you will get inclusions and have to repair. I don't understand why companies would rather chance it on a bad operator and less man power. Get you a couple good stick welders. Turn that thing on its side and let them go at it with a 6010 root then 7018 out (Vertical position).Next Door they have SAW on large O.D. pipes. Been using it for a long time now and cant understand why there are so many repairs having to be made all the time. They store their wire in an uncontrollable environment. It sits out in the open. The hopper with the flux... sits out in the open... the operator....doesn't know what he is doing or he would have all the consumables stored in a dry safe area away from the Mississippi 80-100% humidity lol.Last edited by AndrewDavenport89; 06-02-2015 at 07:54 AM.
Reply:@AndrewDavenport89To answer your question, the steel grade we're using is high tensile strength steel, EQ70 equivalent grade. And yes, the welding procedure that you've described for the double V-groove is what we are doing at the moment. I'm not really looking for a WPS since we have already established it for the current process. Comparing the weld quality, SAW has a much higher quality than the SMAW method. Besides the SMAW requires highly skilled workers (in order to produce really good quality welds) to do the job while the SAW is partially mechanised thus the weld quality is more or less assured. Comparing the weld volume required for both type of joints, the narrow gap joint uses much lesser filler material than the double v groove joint. Along with the benefits of using less man power to achieve more work, that's why the narrow gap concept was considered.Yup, I do agree with you on the issues that may arise due to poor housekeeping / storage by the workers.Thank you for your input too!
Reply:Originally Posted by martianoo@Welder Dave,yes, we have considered issues on single side welding and we are intending to set the work piece in pre-bent position. Currently the joint is a double v groove, so alternate SMAW can be done@AndrewDavenport89,my bad.. initially i wasn't going to reveal it was for a jackup rig, hence i used the term 'steel blocks'. Attached are a prototypes of the joints mentioned. Top picture is the current weld joint which is a double v joint and the welding process is SMAW.Bottom is the narrow gap v joint which i'm hoping to use SAW process for it.
Reply:*SMH* .....And you don't think SAW isn't highly skilled just because its mechanized? I couldn't touch one of those machines because I am not qualified. But there are people who would try and they cant run it to save their life. That is why these people next door are getting so many discontinuities and constant repairs from X-ray for inclusions. A couple stick welders who knew the slightest bit of what they were doing would weld that up better than any "machine". I hate any mechanized form of welding. Takes the jobs away from people who need one.But hey since you have a PQR for it go with it. Just hope you got the right guy running that machine. I think your standing on management side of things looking at cost for filler and manpower. Cutting costs can be risky business. I have seen it countless times.Last edited by AndrewDavenport89; 06-04-2015 at 09:19 AM.