Inspection of Fire Water System

[qaisarabbas]

My friend asked me about the inspection checks for fire water system at a process plant where underground piping for fire water system is not protected thru any type of cathodic protection. Moreover there is no inspection plan for pipe risers of this safety critical circuit. Operation personnel are also not much aware of its surveillance.
My suggestions for his case are:
- Ensuring minimum continuous flow thru fire hoses to avoid blockage
- Inspecting pipe risers to assess corrosion at soil-to-air interface
- CIPS survey to detect integrity of coating wrapping on buried piping
- LRUT inspection for corrosion mapping of underground piping

I would request the knowledge & experience sharing from the forum members.

Regards - Qaisar

[mechcolor]

In addition to what you have suggested, I would recommend to perform periodic hydrostatic test on this line may be after two years. This would ensure the mechanical integrity of the whole piping.

[sakib321]

same problem is here with us on our cooling water system
so what you suggest for it ?


i think LRUT is best one

[mechcolor]

No cathodic protection for cooling water system lines??
LRUT has its own limitations and challenges, do consider that. Follow the link, it would help you somehow http://forums.thepetrostreet.com/viewto ... fbb82#p983

[sakib321]

ya we had not CP for even fuel gas line


in above mentioned thread u refer TOFD
but my question is that is in TOFD we need to excavate the whole line for inspection??

[mechcolor]

I was referring to this:
"Dimensions are OK to qualify for LRUT but for your case of burried piping there are several challenges:
1. In case of LRUT inspection of buried piping, attenuation occurs to a larger extent especially due to soil and presence of bituminous coating which in most of the cases is present.
2. Attenuation leads to lesser inspection length and with one inspection at exposed location you may be able to screen about 20-25 meters of piping length.
3. Contact with soil leads to difficulty in data analysis.
It is strongly recommended that only experienced personnel must report the results of LRUT for buried piping.

I would mention again that LRUT will screen and then you have to use any exact thickness measurement / flaw sizing technique to be sure of actual thickness. If not TOFD, manual UT has to aid LRUT results to make the right decision. Screening is enough in certain situation but normally, you have to narrow down your finding and to come up with right repair procedure.

I hope it would help."

TOFD or any other UT technique just to narrow down your findings after conducting LRUT.

[sakib321]

ya got it now thanks
so is there not any other option other than LRUT ??

[ramlee]

Hi,

I would suggest before jumping into doing expensive NDT... pls consider the following and then only formulate your inspection program

a. Identify the internal threats which is mostly from dissolved O2, Chloride, SRB, MIC, etc and then cross reference to corrosion management system, medium - seawater, brickish water, freshwater..etc, mechanical data such as mech data.... , material, galvanize non galvanize, layout, etc, review of incoming monitoring lab reports if any and fire testing frequency ....
b. Identify external threats - locations of the plant, environmental, atmospherics, mech damage, coatings if any, CP if any, etc
c. Failure history if any.. what, where, how and when

THEN only you formulate an inspection program to validate and trend ( such as general metal lost ..etc )

Pls do not put the cart before the horse

Hope my 2 cents worth make sense

Inspection ToolBox