Inspection Frequency for Heat Exchangers 1

[prchick1984]

I'm working on developing an MIQA program for my plant and can't find anything on how often shell and tube heat exchangers. We've never done inspections on the heat exchangers before, but they have been in service for over 10 years and has hazardous material going through them on once side and then water on the other. I was thinking of recommending 10 year inspection frequency, but can't find a standard or engineering practice to reference. Does anyone have any suggestions on standards to reference? Is 10 years a good number or too soon?

Thanks

 

[MJCronin]

How well have you searched for this information ?

Inspection intervals for Shell and Tube Exchangers are usually in accordance with pressure vessels as defined in API 510 Vessel Inspection Code, Generally, this means inspection at vessel half remaining life, up to a maximum of ten years.

MJCronin
Sr. Process Engineer

 

[prchick1984]

Well that was uncalled for. I thought the reason of forums like this was to ask for advice from fellow engineers. I'm the only one where I work, so I didn't have another knowledgeable person to ask.

I know off API510 for pressure vessels and of other standards, but I'm used to using it for reactors or storage tanks, and I wasn't sure if it was applicable to shell and tube heat exchangers. Why do you think I said I recommended 10 years?

 

[jeevesme]

I don't believe @MJCronin had any ill-intent with his post. He was just saying that it is fairly easy to find what you are looking for. . . . if you know what you are looking for. Heat Exchangers are typically considered "Pressure Vessels" as they have pressure being exerted on both sides. That being said, you would follow API 510.

There are a lot of variables that need to be considered when setting up an Inspection and Test Plan. Heat Exchanger type, process conditions, accessibility etc.

Has a PHA been performed on them? Has an RBI been performed? Are they PSM? Going 10 years between Internal Inspections with "hazardous" material going through them seems a bit off without these having been done.

Perform a PHA.
Determine if it is "business critical".
Determine what damage mechanism it could be subject to.
Create Inspection and Test Plan.
10 years max internal inspection interval
5 years max external inspection interval

 

[prchick1984]

We just finished our PHA on the process, which is covered by PSM. One of the items I had brought up was when was the last time it was inspected, and that's when we saw that it was never inspected as well as a number of other pieces of critical equipment, so one of our recommendations is to develop an MIQA plan for all our critical equipment with frequencies and standards associated with them so we can put them into our system.

The equipment is stainless and we use tower water that we've seen can cause cracking in stainless steel, and if we were to get water into our process, we could have serious consequences. I'm not sure how we got by for so long missing some of these things, but that's what I'm working on now.

Since we haven't had an issue yet, I'm thinking 5/10 would be good, but to have an inspector come in now to do the inspection and then set the clock based off that date.

Thanks.

 

[SJones]

If you want something from the UK to compare, then try:

http://www.safed.co.uk/technical-guides/pressure-equipment/

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[EdStainless]

Remember that not every inspection needs to be comprehensive. If there will be more frequent occasions to have access to some critical pieces of equipment you could also plan more frequent spot inspections focused on critical aspects.
For example I know of a process with a HX that in the past has failed due to inlet erosion. The have a policy in place (and procedures) so that every time this process unit is off line for more than a couple of hours they look at the inlet area of this HX. At first this seemed like a lot, but over the first few years they gained a very good picture of how this was developing and now have a good reliable schedule.
Sounds lime you need to address water treatment and control as well.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy

 

[Dhurjati Sen]

Dear prchick1984,

Why always look for some code or standard or reference?
You are the code.
It is your plant.
You know what is the shutdown frequency.
You know what are the financial considerations (lean / peak season) for taking a s/d or running the plant on a low thruput.
You know about the outages / disruptions / breakdowns.
You have history cards for each equipment (not only exchangers).

You decide on the inspection frequency.
Place it to management. Let them validate it.

Regards.

DHURJATI SEN
Kolkata, India