I prefer Lawrences method of making it easy. I've never been a fan of John's tough love method.

It is also in paragraph 6.11 on page 212 of D1.1:2006.

Ctacker
Good!  now you need to do 4 things. First -   Look up the correct answer to the ones you got wrong.  Look at all the referenced paragraphs found when you are looking up the answers. Look up the key words in the index, until you get back to the answer to your question.  Then go to the front of the Code Book to the Table of Contents.

Second -  Do the same thing for the questions you got right.

Third - If your question takes you to a table or figure, either directly or through reference, you must learn how to use these tables or figures.

Fourth - look at and study the paragraphs before and after the paragraph you find your answer in. Follow all the references, and the Commentary just as in 1 above.

I feel your pain about other incompetent welding inspectors.  This is one of the reasons I get so short tempered when future CWIs try to get test question help on the Forum.  "Last week, ah caint een speel welding inspoctor,  Now I are one!

Funny thing how codes in North America differ.  CSA W59 (Canada's version of D1.1)  states that, "Visual inspection of welded joints subject ot high restraint and/or joints of quench and tempered steels shall be delayed as long as practicable and preferably no less than 48 hours after completion of welds." 

When working to this standard you rely heavily on the ability of the client be open minded and willing to listen... sometimes they like to define practicable using their own rules.

There was also a great article in the WJ a couple years back (Nov 2003) about this topic titled, "Evaluation of Necessary Delay before Inspection for Hydrogen Cracks" by R. Pargeter

Sean

(These are based on theories of various things I have learned over the years and may be incorrect)

There are two things to worry about when welding on  HSLA steels as far as heat input goes

1) Not enough preheat resulting in residual stress, hydrogen embrittlement etc. This would cause a rapid heating and cooling cycle. I am pretty sure you have to get to a certain amount of stress before this causes problems (not considering hydrogen). Carbon Arc gouging does rapidly heat and cool the base metal however the residual stress that results from gouging is probably negligable compared to welding since there is no contraction of molten metal involved. Since none of the molten metal remains in a carbon arc gouged area , hydrogen is not easily absorbed. In cases where preheat is too low, problems encountered from #2 below are not going to happen.

2) Too much heat can nullify the effects of the "Quench and Temper" process that A514 goes through. This could be likened to annealing. It reduces the yield strength and may affect the ultimate tensile strength. For this to occur, the base metal has to reach a certain tremperature for a certain time. The max temp that the base metal reaches during Proper Carbon Arc gouging in VERY low compared to the temperature met during welding. Since the time and temp is so long, overheating is unlikely. In cases where the max time at temp is too high the problems encountered in #1 above are not going to happen.

I have arc gouged quite a bit of A514 and followed up with MT with no cracking. One thing nice about the effects of #1 above is that it can be found out at a later date since it usually results in cracking. With #2, there is no visual evidence of the parameters being exceeded. Just reduced mechanical properties.

With a preheat prior to gouging you are that many more degrees closer to that "Maximium time at temp" that was mentioned. Oxyfuel goufging is often prohibited on quenched and tempered steel. A large area must be heated and held at temp before the metal becomes molten. This "softens" the material.

There is a balance that should be maintained with HSLA Q&T steels.

Not enough heat>rapid cooling>Hydrogen trapped>residual stress=Cracks/Too much heat>Reduces Mechanical Properties>Not visible by normal NDE= Fails in service due to yielding.

I can Alawys easily eliminate one of the two above by pushing the parameters . A VERY high preheat which results in a higher maximum temperature and slower cooling rate will reduce the chances of cracking. A process in which the maximum heat input is kept low and the weld/base metal heats and cools very rapidly, reducing the mechanical properties is very unlikely.

Each application of welding process needs to be closely evaluated for the service in which it will be used. If there is any question, conduct a PQR both ways.

Gerald Austin
www.weldingdata.com

Dear
Quenched and tempered steel is very problem repair, beacuse no controlated heat result in low strengh and impact toughness.
Is importan controled minimum preheat and max interpass and heat input.
I recomend other WPS for repairs with  PQR and review result test.

Regards