30" Alloy Steel Pipe - Crack Problem

Put an appropriately-temperature-rated pipe repair clamp around the outside of it.

Either that or shut the line down and replace it now.

we are looking for something other than clamp

the line can not be shutdown with out a total shutdown. because we have a overhall about in 2 months we want to control the crack up to that date

Remember Flixborough?

TURN IT OFF AND FIX IT NOW, BEFORE SOMEONE GETS KILLED!

Your Company is flirting with disaster. You have a high temperature, high pressure line with hydrocarbon/hydrogen mixture in it. This is a bomb waiting to go off and your company does not want to shut down early and fix it.

Here is another example of the same type of fuzzy thinking.

The year: 1979

The place: Refinery complex on the south coast of Puerto Rico

The unit: Platformer

The scheduled shut-down: Monday November 19

The problem: Leaking seals on the high pressure charge pumps (had been leaking for some time)

What happened? The seals failed completely on November 15 (four days before the scheduled shutdown) and the resulting fire destroyed 90% of the Platformer Unit, equipment, piping, structures, electrical and instrumentation. Fortunately nobody was injured of killed.

Was the delay worth it?

i know it is very risky

as my department (technical inspection) decide to start overhall ASAP

but some others disagree

may i have the exact information about the that case you mentioned

i want to use it as a witness for the dengerous we have

You asked the following:

"May I have the exact information about that case you mentioned? I want to use it as a witness for the dangerous situation we have"

After more than thirty years I don't think there is much left. I am no longer working for the Company I was then. The company has moved twice in that time.

Back then, I was in-charge of replacing all the piping for the plant. I recently tried to look at it on "Google Earth" and it was not there anymore. But it was there and it did burn because of greed and that bad decision.

What is the pressure?

less than 2 bar

but the temperature is 400 C

I have made emergency repairs on lines containing H2+CO at anywhere between 80 and 900 degrees C and 1.5 to 2 barg - most people get frantic about it but it can be done safely. 400 deg C or not, as soon as a welder starts work it will be burning.

We would weld a pipe coupling on and then weld whatever crack still appeared outside the coupling - we could reduce the pressure for a very short period to something like 250 mbarg and restart easily so we would do so and turn a plug into the coupling.

Great care was made to see that the system pressure stayed in the range we required - a guarantee that the system stayed at a positive pressure. As long as the gas is escaping from the pipe to the atmosphere you are not in an explosive situation.

Great care must be taken to protect the workers from the gases - any CO or CO2 requires attention (plus whatever else you may have in the gas stream). We use large ventilation fans to insure the gas flow was away from the workers.

Any work around leaks like this has to be controlled by a very senior man standing on site and controlling the activities - not from an office.

There will probably be a raft of people crying how horrible this is to do - but I have done it many times. The technology company office back in the US would be up in arms when they heard but that was their problem.

sorry can you explain more and give us picture about your techniq

by the way the pipe material is 1 1/4cr + 0.5 mo that cause a very brittle material

welding may cause extending the crack

We were always dealing with ASTM 515 type of material. I can not tell you about the material you have.

Your maintenance people should know if they can weld that material. If they tell you yes then I can try to explain in more detail but the way we did it it is very simple.

No pictures available as I am retired now and no longer in the plants.

the material is A691 and all alloy steels are welding sensitive

we finally shutdown the plant and put a reinforced pad on it

thank you all