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Oregon Jim
05-04-2008, 04:44 PM
Scenario;

During routine maintenance you remove old wet insulation from ammonia piping and find both pitting and corrosion. How do you judge or determine whether the pipe should be replaced? Is there a specific code that says a certain amount of corrosion is tolerable, but beyond a certain threshhold the pipe must be replaced?

One person says "There is plenty of metal left in those pipes. Clean and paint them, and reinsulate them. They will last for years."

Another person says "That corrosion scares the stuffing out of me!"

What is the standard? I would appreciate your assistance VERY MUCH with this....

US Iceman
05-04-2008, 05:38 PM
The standard (of sorts) is B31.5. This is the ASME code for refrigerant piping. It does not specifically state what you should do or not do however. It is only a design code that requires a lot of interpretation.

First you need to calculate the minimum wall thickness to contain the design pressure and stresses induced in the piping. (warning: this is fairly intensive). This also presupposes you know the pipe material and schedule.

Once you have the minimum required wall thickness you now know this is the minimum thickness you SHOULD allow in the your piping.

If the wall thickness in the pipe is less than the minimum calculated thickness available in the pipe, it should be replaced.

With this procedure you at least know what you are supposed to have versus what you do have.;)

Then when installing the new pipe make sure it is cleaned and painted and a good insulation system is installed (vapor retarders, sealed joints, etc.).

In my opinion the insulation is extremely important. If the vapor retarders leak due to poor installation practice you will be replacing pipes again. This gets expensive, not to mention the fact that you now know the pipes are corroding and a least expensive option was chosen.

Closed cell elastomeric insulation is not very good on ammonia systems. Stick to Styrofoam or equivalent.

gwapa
05-04-2008, 08:58 PM
Jim
Please visit the following page it will help you to calculate the pipe thinkness required
http://www.ajdesigner.com/phpironpipe/wall_thickness_equation.php

Regards
gwapa

gwapa
06-04-2008, 02:03 AM
Jim
Some time I like to sleep well without any worry

If the pipe is a small pipe I will change it and sleep well

If you have a big suction pipe some time I have required a NDA (Non Destructive Analisys). We use an ultrasonic method to detect the minimun wall thinckness. You have to be aware that the pitting could be very deep some time.Becareful

After that came the question: What happend if you have a big leak and you knew the pipe was corroted?
What will happen if somebody dead?

I prefer change the pipe.It cost nothing
Gwapa

NH3LVR
06-04-2008, 02:19 AM
This brings up the issue of Vapor sealing and its importance. I removed some suction line that was 30 years old. I had insulated it with Aramflex closed cell myself. The pipe was painted before the Aramflex was applied.
After 30 years the pipe was in good condition. As I recall we used flat sheets cut to size and glued it to the pipe.
Of course this plant runs 24/7 so the line was always frozen.
This is a success story. Your results may vary.
I know of one company in the cold storage construction business that does not paint pipe, nor do they vapor seal the plastic jacket. It looks OK from the ground, but if you climb on top of the vertical vessels you will only see foam.
10 years-probably OK
15 years-maybe OK
20 years-not OK

mctavara
06-04-2008, 04:16 AM
Hi Jim,

I agree to NH3LVR. The best practice for pipe installation especially NH3 refrigeration plant is Coating the pipes (remove rust then painting) first before introducing PU foam or insulating styrofoam. I saw some installation here in KSA wherein the -25 C liquid line manifolds last only for 7 years because of corrosion due to lack of primer coating of pipes.

Cheers to NH3LVR

Oregon Jim
06-04-2008, 04:59 PM
This is my situation...

During routine maintenance I removed a small section of old insulation from the bottom of an LPR to replace a small piece of pipe that I knew was badly corroded, but removal of the insulation exposed more corrosion, so I went to my superiors asking permission to remove more insulation for further inspection. There is ABSOLUTELY NO DOUBT that the remaining insulation is hiding more (and possibly worse) corrosion, and this corrosion is in my view extremely bad and dangerous.

Management immediately went into panic mode because:
1. Removing and replacing the insulation is a big dollar expense.

2. Removing insulation MIGHT EXPOSE much more corrosion and danger, which also translates into more money.

3. Timing is bad. We are looking at production beginning in just over one month. Repair might take much longer, especially if corrosion is as bad as I suspect.

The company sent the head of the refrigeration department to look at the piping and he advised that we should just paint the exposed piping, re-insulate it, and put off repairs until next winter. I believe that doing so creates a terrible risk to all of us.

As of last Friday, no decision has been made as to what we will do. We had a contractor out to estimate the cost of reinsulating my LPR's and related piping, and he told me it would be expensive to do both receivers, so there is a good chance that my company will make every effort to remain ignorant of impending unseen danger and to put off or make minimum repairs until next winter.

I (and others) have considered calling a regulatory agency such as OSHA if the company refuses to inspect and repair the piping, but there is no doubt that this would endanger our jobs, and there is the further danger that if the regulatory agencies become involved that they would create a nightmare situation much worse by shutting down the entire plant and inspecting every inch of the facility.

I am just filled with worry... I cannot ignore or cover up the corrosion I have found, and I am not in a position of power or importance where my opinion carries much weight in financial decisions, and this is a big one. If the company does inspect and they find the damage I suspect is there, it will cost a great deal of time and money to repair it. If we do not make repairs there is a HIGH RISK of pipe failure and injury or death to those working nearby.

In short, safety and money are in direct competition, and I believe that safety is to be second place. I am truly worried.......

US Iceman
06-04-2008, 07:12 PM
I can empathize with your situation, but this is EXACTLY why PSM is so important. It's purpose is to catch this issues before they become problems and someone is injured.

Management doing this:

http://spiralcastle.net/aw/ostrich.jpg

does not relieve them of responsibility.

And, if they think replacing the vessels, piping, and insulation is expensive wait till they get a willful violation issued against them from OSHA.

Someone may be running the PSM program, however management is still the responsible party. Only they can make the decision to spend money, so if an accident or release occurs they will be the ones escorted off the proprty in handcuffs.

gwapa
07-04-2008, 01:17 AM
Jim
You are a technician and you have to support at the manager in his desicion.
You have to send a Memorandum where you explain the situation and the risk involved. Leave every by written.
Increase the safety . Install eyes shower,body showers. Keep the ammonia mask and filters in good shape. Keep every thing you will need to fight agains a leak in good shape. Emergency Light for the night. Scape route, and so on. Every thing have to be in good shape. Also review the emergency procedure and
Good luck
Gwapa

nh3wizard
07-04-2008, 02:52 PM
Oregon Jim do you have any pictures to share? I would just make sure you had everything "well" documented, Especially emails, there has been more than one occasion that a email has saved my butt.

Oregon Jim
08-04-2008, 01:55 AM
There was no news from management today, but I heard through the rumor machine that repairs are being planned. It is much too early in this process for me to get all worked up, as no decisions have been made. I do have faith that there are people doing their best to get this right. From what I have heard, my supervisor's advice to paint and cover up was not received well. I promise to keep you updated.

I considered posting some pictures, but I think it would be rather unethical and I am certain that my company lawyers would have a serious problem with it. Perhaps after the bad pipe has been removed I may be allowed to take pictures for later reference. I really like my company and do not want to portray it in a bad way. There are lots of hoops to go through when you are spending company money, so decisions don't often come quickly....

US Iceman
08-04-2008, 02:29 AM
There are lots of hoops to go through when you are spending company money, so decisions don't often come quickly....


That's about the same everywhere. The safest bet right now is to not post any pictures. You asked for comments and received those, which is fair and does not give anything away.

Hopefully, the comments you received helped you and/or your firm and they were taken constructively without getting your rear in a sling.

zolimer
08-04-2008, 02:58 AM
Jim,
Your job is to recognize the importance of these issues! Their job is to take your word for it, or to fire you and listen to some one else! As was mentioned in an earlier post, try to use technology to your advantage (ie.. email) to CYA (cover your ass)!

You cannot be expected to be held responsible for your superiors decisions but you should recognize the risks and have a contingency plan! I guess the argument could be made that you must prove to these people that you have an intimate understanding of your knowledge of the subject! After all isn't that why they hired you in the first place?

You have said that you wrote the PSM/RMP @ your facility! If that is true than your employer trusts you with the regulatory side of things! They should trust your judgement on the preventive maintenance side of things also! Even if it means spending money! Just my two cents! Regards Tim,

NH3LVR
08-04-2008, 03:07 AM
Oregon Jim;
I might comment that I do not make my location public in my profile. This leaves me a bit freeer to comment on issues. I belive you do know my location, as do a few others.
I have been in your situation before. It is an uncomfortable one, but sometimes you just need to accept the things you cannot change. We do not like it, but sometimes it is what it is. If you leave over it they will find someone else to operate the plant who will not care at all.
Corrosion is a difficult problem. It tends to look worse than it is. The worst usually occurs at the outlet of a vessel. If you can pump the vessel out and pick away at the bad spot you can get a better idea of what you are up against.
If you do poke a hole through while inspecting you were right from the begining.
I do not envy your position.

brian_chapin
14-04-2008, 04:42 PM
You might want to consider painting your new pipe with Macropoxy or an equivalent two-part epoxy before insulating it. We now require it on all refrigeration piping and are very happy with the results.

Oregon Jim
18-04-2008, 04:25 AM
Here is an update...

I finally received the okay to strip insulation from my largest LPR and related piping yesterday. We stripped the receiver, liquid NH3 feed line, suction line, oil drain lines, pump suction and discharge lines, and we began cleaning it all with a high pressure washer. The receiver and all of the larger piping are slightly pitted, but not to a degree that concerns me. However, I have uncovered some very bad corrosion and pitting on some of the other piping. I am immensely pleased that I have been given the go-ahead to do what I knew was right from the start, and I am annoyed that management dragged their feet so badly on this, but as of this moment it looks like things are moving in the right direction. I will complete the clean-up of the system and invite all of the bosses over to see what I have discovered.

I really wish that it would not be such a violation of policy to post pictures of what I found, but in these days of lawsuits and litigation no company would allow it, and I don't blame them. What is important is that those decision makers are doing the right thing and that we will all be much safer.

I would like to say that the cost of insulating this receiver seems astronomical to me. I am sure glad that I don't pay the bills... Large numbers scare me!

US Iceman
18-04-2008, 05:57 AM
It you want cheap insulation, you really don't want it at all. The insulation and vapor retarders are the key to protecting the vessels.

The moisture and oxygen that caused the corrosion came from somewhere. You can't do much about the oxygen, but the moisture prevention is a different story.;)

Oregon Jim
22-04-2008, 03:09 AM
Another update...

We finished cleaning the first receiver and its piping, and the piping is just terrible.

I am dumbstruck!!! Again my refrigeration department manager has recommended that this corrosion be covered up without any repair. He said we should paint it, insulate it, and forget it. An insulation contractor has been called. Paint has been ordered. No effort is being made to test, measure, or repair anything. What is even worse is that I have been told not to remove ANY insulation from the second (older) receiver, as they do not want to know anything until next year.....

I am afraid that my days at this company are all but over as I intend to bring in OSHA if repairs are not made. My choice is to ignore danger and hope for the best, or to do the right thing and risk my career.


Life really sucks sometimes.

US Iceman
22-04-2008, 04:00 AM
Having a potential problem and not knowing about it is not as bad as knowing about it and doing nothing (or covering it up, if you'll pardon the pun).:(

Having knowledge of problem and completely disregarding it because it is inconvenient, not in the budget, or any other excuse could very possibly be seen as a willful violation of PSM. This is when the big bucks for penalties come into play (or arrests).

Being a whistle blower has the obvious effects of correcting the immediate situation, or worse yet... having OSHA uncover a lot of violations and shutting the facility down for safety reasons. None of this includes anything the EPA might consider also. I understand your situation but the potential blow-back for you is very real. It might be better to document everything you said, where it was said, persons involved, and the date and time the conversation occurred.

No matter what, management is the responsible party. not you. If the crap hits the fan the documentation you collect could be used as evidence on complicit actions on their part.

This is why PSM states a person shall be responsible for the PSM program. This does not mean the person doing the work, it is for the person who can make the necessary decisions to implement any changes to promote safety and to contain the ammonia.

Now that you what is happening I'm sure it will be like walking on eggshells. If it bothers you bad enough, you might consider talking to an attorney for advice to CYA.;)

Painting over corrosion is just throwing money away as a false sense of security that everything was done.

Oregon Jim
22-04-2008, 04:26 AM
I have but one last resort. That is to take this issue to the Safety Committee and hope that the committee will make an effort to resolve this. I will make my case on Wednesday, but I am certain that I will face severe retaliation somewhere down the line. I am sooooo depressed....

I have documented all I can, but the hard truth is that the committee is unlikely to to prevail. I am the one that will probably be hurt first if there is a release because I am the ONLY ONE qualified to perform maintenance on our system, so, having documentation and saying "I told you so" will not make me feel one iota better if someone is hurt or killed, especially if it is me....

I discussed the situation with my wife. The worry over losing my job for bucking the system is real. Luckily for me, I married the best woman in the world and she is willing to support my decision regardless of the consequences. As I said, I am deeply depressed over this. Work should not be so stressful.

Oregon Jim
25-04-2008, 06:02 AM
Wednesday was a tough day for me. I presented a formal letter to my boss explaining my serious concerns about the piping. I'll save the details, but I was respectful, specific, and made my case. Management was faced with conflicting opinions from a supervisor with forty years experience, and another with just twenty years. They chose to do the only smart thing. They called in an engineering firm to examine the piping and he inspected this afternoon. Again I will save the details, but I believe his report will strongly support my view that repair must be done immediately. I should hear something on Monday.

I am proud of myself but apprehensive at the same time because I know this is bad news at a bad time for my company. Production season is just around the corner and this is way beyond inconvenient. Also I fear that I may have opened a whole kettle of worms. After all, how far does this corrosion problem go? I don't know yet and we may be forced to find out now what me might prefer to find out after harvest, if you know what I mean.

There isn't a shadow of doubt that I have done right by exposing this. It is my job and I am very happy to do it, but I fear the cost to my company will be high. It won't be a fraction of what a pipe failure would, but it will be painful and I am sorry. I like my company. I am guessing that next week when the engineer's report arrives it will be illuminating event for some. I just hope this is not too serious a blow to the company.

I will keep you informed. I applaud management for doing the right thing.

US Iceman
25-04-2008, 05:00 PM
It's always painful taking the right approach. Anytime you tell someone something they would rather not hear is not much fun.

Management may not like what the engineering company has to say but... this helps to highlight the reason for doing mechanical integrity inspections so that these issues can be addressed in a reasonable manner at a more convenient time.

Tycho
25-04-2008, 09:45 PM
if there is not much pitting, a good way to judge corrosion by eye is to use a spanner, hold it tightly in your hand and tap the pipe quick and gently...

if the pipe "rings" it's ok (rings = diiiiingggggggg) :D

if it does not ring, sounds like you just hit a wet newspaper, it's past time to be replaced.


I have used something called "Rustbear" it's a milk like liquid you can apply to the pipes using a brush, it reacts with the rust and hardens. you should clean the surface of loose flakes, but if it's a hard to reach, you don't really need to do it.

also on welds between stainless (316) and black pipe I have had some bad experience on untreated welds, so now I paint them before insulation with the same primer they use on the hulls with good results.

here's a picture I have posted before, you can see the carbon pipe and the stainless weld, notice how the corrosion has eaten it's way under the weld where the pipe has been heated by welding
http://www.pbase.com/kimmo98/image/55787497.jpg

jjpeterson
18-11-2010, 11:22 PM
Yes there are standards. Check NACE
If more than 50% of the surface is rusted, to any extent, then the amount of metal lost cannot be determined by visual inspection.
The surface must have the rust removed and the thickness of remaing pipe wall determined, xray, ultrasound, or whatever.
If the remaining wall thickness is less than that required by the maximum working pressure plus one half of the orininal excess, the pipe should be replaced.