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Up Topic Welding Industry / General Welding Discussion / CHILL WATER HOT TAP
- - By Bleonard1088 Date 08-01-2017 20:04
I am doing my first hot tap on a chill water main ina couple of days and could use some insight. Due to the low temperature and condensation on the pipe I was wondering if it would be wise to use 7018 rod the whole way out to reduce the chance of hydrogen cracking. If anyone has hot tapped a chill water line before any information would be greatly appreciated. Thank you
Parent - - By 803056 (*****) Date 08-01-2017 20:36
Low hydrogen would be my first choice.

What does your qualified WPS say on the subject?

No qualified WPS? What the heck are you doing welding without a WPS?

Parent - - By Bleonard1088 Date 08-01-2017 20:47
The company I'm working for does a lot things like this for the facility without any prints so there will be no prints or weld specifications unfortunately
Parent - - By 803056 (*****) Date 08-01-2017 21:29
It is a shame an employer takes on work they are ill prepared to do and when things go wrong, blame the problem on the welder.

It is negligence on the part of the owner for not hiring an engineer that understands the nature of the work, what the code requirements are, preparing the necessary drawings, and allowing the owner to hire contractors that do not have the necessary staff to perform the work correctly. Again, when things go wrong, it is the welder that takes the fall.

Just my thoughts.

Parent - - By Bleonard1088 Date 08-02-2017 02:12
You're right, it is a shame. But it needs to be done reguardless. So if you have any other recommendations I'd appreciate anything you have to offer.
Parent - By dbrizor (*) Date 08-04-2017 12:43
Sometimes welders have to do what welders have to do to get the job done (even without support). I get it. Happens often sadly! That's one great resource of this forum.

Not sure I can help much with the little info. But, first thing I would do is determine if preheating is an option for the application (torch, blanket, coil, whatever). If so, preheat/weld (you may need a guy leading and trailing the weld joint while welding is being applied-flames angled away from the weld arc). E7018 should be fine for standard low carbon pipe.

Welding is my specialty not CWHT so take this for what it's worth. Just hoping to help out.
Parent - By Joey (***) Date 08-15-2017 01:29 Edited 08-15-2017 01:32
Al is correct that you must have the approved WPS. But I think before you ask for welding consumables, you should find out if
there is a detailed written plan prior to performing this work. It's called "Hot Tap Procedure" that normally the owner-user wants the contractor to submit for their engineer's review and approval before the work commence.

This could be helpful.

Electrode Considerations

Hot tap and in-service welding operations should be carried out only with low-hydrogen consumables and electrodes
(e.g., E7016, E7018 and E7048). Extra-low-hydrogen consumables such as Exxxx-H4 should be used for welding carbon
steels with CE greater than 0.43% or where there is potential for hydrogen assisted cracking (HAC) such as cold
worked pieces, high strength, and highly constrained areas. Cellulosic type electrodes (e.g., E6010, E6011 or E7010)
may be used for root and hot passes. Although low-hydrogen electrodes are preferred, some refining locations and the pipeline
industry prefer to use cellulosic electrodes frequently because they are easy to operate and provide improved control
over the welding arc. Root pass with low-hydrogen electrodes reduces risk of HAC. It also reduces risk of burnthrough
because the amount of heat directed to the base metal is less than when using cellulosic type electrodes. However,
manipulation of low-hydrogen electrode for root pass is not as easy but it can be done by training and practice. It should
be noted that cellulosic electrodes have the following adverse effects on the integrity of the weldment:

a. Deep penetration, therefore higher risk of burn-through than low-hydrogen electrodes; and
b. High diffusible hydrogen, therefore higher risk of hydrogen assisted cracking.
- - By 803056 (*****) Date 08-04-2017 13:19
We tend to overlook the legal ramifications of our actions. There are laws in place that are there to protect workers and the public. As I've said before, no one cares until there is a failure and property or people are injured. Then the lawyers come out of the woodwork to sort things out. Everyone is made to suffer, including the welder that "followed" directions.

My job in such situations is to make the client aware of the shortcomings of the work that was performed. Was the WPS properly qualified? Was the welder qualified? Did the work comply with the requirements of the code? It is amazing how easy it is to make the case that those three items were not met. End of story, pay the plaintiff please. It is also amazing how often the defendants (contractors) involved are well aware of the legal requirements, but choose to ignore them in the pursuit of profits.

While the welder performing the work is insulated provided he is an "employee", he will still be subject to questioning during "discovery" and can be charged with perjury if he makes a knowingly false statement in an attempt to "protect" the employer or himself in a criminal case. Most cases are not criminal cases, most are initiated by a plaintiff that suffered a "loss".

These cases usually fall apart very quickly. Only one of my cases went to court. Usually the cases are settled out of court. I am happy to say all my cases have been settled in my client’s favor. Sad to say that it is a slow, costly process. That being said, it is tough to hide the truth when there is physical evidence to examine and everyone on the project is subject to questioning by both legal teams.

Even if the contractor did what was required, the costs can spell financial doom. Insurance companies don't care to provide coverage for clients that have incurred claims. If the contractor can not find an insurer, he's effectively out of business.

Parent - - By yojimbo (***) Date 08-04-2017 17:38

You might try using the search function to find some practical, applicable information to do the weld you are tasked with.  I searched under "chilled water" and there are several threads that will at least direct you to information sources that may be beneficial.  JR Wright is someone with practical experience and in my own experience JRW has always been helpful providing expert insight.  That said, the consensus regarding "hot taps", which are the most common discussion, is they would require a qualified WPS.  I can't remember where the discussion was but I do remember some welders/inspectors talking about a weld test that required a welder to do exactly what it is you need to do in practical application: they had to weld a branch onto a main that had water flowing through it and lowering the pipe temperature.
All the experienced welders who had performed the weld you need to do agreed using 7018 with the smallest rod diameter to maintain the highest heat input but also mention that at conclusion of the weld they could put their bare hand on the weld- it had cooled that quickly.
What size main are you welding to? Branch size?  Wall thickness?  Steel grade? Line pressure?  In your boots I would at least like to know those factors.  Would I do it?  As an employee, absolutely.  I'd make sure to inform the highest level of supervision I was working under of the potential for failure in the strongest terms possible, and then I'd do my best and not give it a second thought.  As an employee you do not carry the responsibility for negligence, that responsibility it the contractor's.  Inform them in writing and your ass is covered, tucked and sweet as a rose.  As a contractor I wouldn't touch it with a 10 foot anything- unless I'd qualified a procedure based on all the necessary information- but that would take money to establish and it doesn't sound like either the people you work for or the owners they contract with are willing to spend the money.  That falls under the heading "Not your problem".  If you refuse to do it, it might cost you your job.  I can't begin to count the jobs I've left for one reason or another but then I prefer sanity to stupidity.  If you do it and it fails, you might lose your job anyway when they blame the failure on your lack of skill and not the real culprit: their greed.  And of course it's certainly possible, using common sense to keep it hot, dry and "properly" welded you might pull it off and be the hero everyone remembers as the guy who did the impossible [especially enhanced after you'd warned them of the many difficulties and dangers and potential for failure].  Use the search function and research this some more before making a decision is my opinion/advice.
Parent - By 803056 (*****) Date 08-04-2017 19:29
Amen! Well put.

Parent - - By Bleonard1088 Date 08-04-2017 19:35
Thank you for your input I really appreciate it. I have been welding for several year but am a brand new apprentice for a local union. So my boss knows I have prior welding experience and asked if I wanted to do it or if he should hire someone else to come in. So of corse I am going to step up to the plate. It is schedule 40 pipe. It will be a 4" weld o let fitting with a gate valve on 6" pipe. I would like to preheat it but don't quite have the resources or man power to do it. I'm kind of on my own fr this one.
Parent - By lo-hi (**) Date 08-12-2017 01:00
There is a weld standard for attaching thread-o-lets, a 4" will take out over half of the pipe of the pipe. Look for isolation valves to drain a section, or stop the flow and use a freeze kit. That much cold water flowing will chill the weld and it will crack and leak anyway, and then you will have to drain the system.
Parent - - By Bleonard1088 Date 08-04-2017 20:15 Edited 08-04-2017 20:17
And not for nothing I tried the search function before creating an account and posting. I could not find much substantial information, hence the reason for my post. People like 803056 seem to love filling threads with nonsense unrelated to the origanal topic.
Parent - By Paladin (***) Date 08-04-2017 23:59
803056 went to the trouble of replying, trying to inform you, of how things are today and was directly related to your little situation. Like it or not he is right. Your statement  was rather small minded. Don't ask a question if you may not like the answer.

Yojimbo also gave you good advice.

You sound like you don't have that much experience, an apprentice. If you have the option of someone else doing it, let them and learn from them doing it.

Welding on a chill water line will not be like what you've done before.

Parent - By welderbrent (*****) Date 08-05-2017 02:09 Edited 08-05-2017 02:13
Well....I was going to offer some advice, but to the unlearned and unwilling to learn about how things work in our industry and the current sue happy environment it would be wasted typing.

There was NO nonsense and it is totally related to the original topic.

Leave a note so someone knows where to send your remains when it is all done because the powers that be will throw you under the bus in a heart beat.

Just wait until it is a natural gas line with gas flowing through it.  Or, jet fuel along the new addition at the airport with people standing there watching out the windows while you do a hot tap. 

Proper procedures will save your life, those in the vicinity, and get the job done correctly.  It has been done since before you were born.  I used to do it, in the 70's and 80's.  But, your too good for that so just go ahead.  BTW, there are codes that address hot taps.  You find them.  I don't have time.
Parent - By yojimbo (***) Date 08-05-2017 17:04

Yeah, uh, well there are a few things you might want to reconsider when addressing or asking questions on this forum.  One of them is that there are a lot of people who participate here that have decades of not just experience, but decades of senior level experience, so while you might not appreciate the breadth of their perspective, and their replies might seem to include issues you see as unrelated to your question, their years of experience have educated them to see things in a broader context. 

That said, their experience and expertise does not always make them correct in their opinions but it sure as hell does obligate you to consider their opinions objectively and if you disagree with their opinions you would be further obligated to have solid, informed, factual, documented evidence to base your disagreement.  And like any voluntary caucus or investigating gathering it's never really a good idea to have your introduction to that gathering tattooed with the memory of the insults you introduced yourself with.  That's just sociology 101.  Go back and review your class notes on that subject.

The very best advise you have been given here is to have a more experienced hand do this chilled water tap.  The reason: your original post does not identify you as an apprentice.  As an apprentice you are expected to learn from experienced hands every bit as much as you are expected to step up and accept progressive responsibility.  Your real opportunity here is the experience of a real life, practical education.  You should be assisting in this tap as the journeymans helper.  You will be able to watch how it gets done and by watching you will learn how to do it next time.  There is never any shame for an honest man to recognize his limitations so long as it is clear he is looking to expand his abilities.
Parent - By Lawrence (*****) Date 08-17-2017 13:02
You are an apprentice...

A puppy.

Puppies are often motivated to please...  Ok, so you want to make the boss happy.

Puppies also tend to bite the hands that feed them... You did that too.

Your boss "perhaps" asked you to do this because you are ignorant of the danger involved.

You have been given sound advice (to walk away) from some of the top experts in the world on this subject.  People who have influenced the construction codes and safety standards you choose to ignore.

Even if you take every bit of technical advice given here by these experts... You will still know nothing near enough to be competent to do the job at hand.
Parent - By jrw159 (*****) Date 09-06-2017 12:34
Have at it and good luck!

Parent - By waqasmalik (**) Date 09-06-2017 16:03
Mr Bleonard

You have been so disrespectful to the prestigious members of this forum family. You used bad words about the legendary 803056. Its so ignoble. You dont like advise, go and try what you want. Whatever you have been advised here is proven and tested. These guys have tons of experience. You are not allowed to disrespect the Worlds greatest mentors serving the humanity. Go give a try as per your understanding.
- - By 803056 (*****) Date 08-05-2017 01:18 Edited 08-05-2017 03:21
Well, I guess if he's only an apprentice ......

Some people have to learn the hard way.

They asked for volunteers, everyone step back. He was left standing alone in the front. I think I saw that in a comedy once. 

Parent - - By Northweldor (***) Date 08-05-2017 13:28
With this attitude, and his apparent inability to read, combined with the failure to recognize that he should not do tasks beyond his skill level, simply because his employer asks, I think he will become a prime candidate for Darwinian selection!
Parent - - By 803056 (*****) Date 08-05-2017 13:43 Edited 08-05-2017 17:38
At least it is chilled water and not something that could destroy a city block should it fail.

Darwin called it.

It would be better if he assisted someone that was proficient before breaking out on his own, but some people have to learn the hard way.

I remember building my first nuclear bomb. I followed the directions I found in the internet. The Sahara Forest has never been the same since.

Parent - - By jrw159 (*****) Date 09-06-2017 12:35
  At least you tried.

Parent - By 803056 (*****) Date 09-06-2017 19:13
That's all any of us can do.

Up Topic Welding Industry / General Welding Discussion / CHILL WATER HOT TAP

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