Pipe on Operation Surface Cleaning

Near white blast should be fine. The abrasive is aluminum oxide, although I don't know if you need to use that. A relevant internet search seems to indicate that traditional sand blasting is quite common.

Since the pipes are in use, if there is the possibility of any flammable gas present, you may need to look into wet blasting...........it's a water sand mix. With a dry blast, electrostatic discharge from the media can create an explosion hazard if flammable gas is present.

there is a possibility for flammable gas inside filling hall. so should we go to wet blast.?

That's what I would recommend, yes. Here's an idea of how it works, if you haven't seen it. It adds water to the cleanup, but it also eliminates dust, and most importantly, explosion risks.

http://www.youtube.com/watch?v=UB2a_8nApPU&feature=related

I think you should consider hiring a company that uses a dry ice blaster system.

Dry ice blasting - Wikipedia, the free encyclopedia

Dry ice is the way to go they use that in our local wire mills to clean varnish off the coating ovens, it saves them big money on the hazardous waste disposal.

Dear Naif,

Your specification "Near White Blast Cleaning SSPC-SP10" is OK, and therefore, you have to specify sand blasting up to grade Sa 2-1/2.

Note: if sand blasting is forbidden at KSA, due to silica which cause Cancer, you can specify sand blasting by grit, which is special type of abrasive but is expensive.

See that very important coloured picture for Sa 2-1/2 extracted from standard "Guide to Pictorial Surface Preparation Standards for Painting Steel Surfaces": SSPC_Guide_to_Visual_Standard Sa 2-1/2.

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Pros and cons.

http://www.osha.gov/dts/maritime/standards/guidance/shipyard_guidance.html

Thank you all. we specify SA 2.5 for surface preparation. but I am looking for the safety of this operation.

LPG is considered flammable material and the area will be hazard. so this operation " near white blast" or any method of blasting can be done on pipes containing fluid like LPG???

the temperature is important but I thing it will not accessed 50 C .so there is no problem about increasing of temp. but if there is any spark from the hoses or machine itself. this is big problem to us.

You can do sand/grit blasting while the LPG line in operation. But before applying the blasting you have to check the pipe wall thickness at several locations, to check its capability to withstand inside pressure of LPG and also to check that it have enough thickness to compensate thinning of pipe wall while blasting. The only problem is when the thickness is very thin it will cause explosion when apply the blasting.

Note. At 1985, the bigger gas plant field at Egypt was sand blasted and painted while the plant in operation. And a daily work for sand blasting and painting for a lot of piping systems in a lot of oil refineries is still carrying out, taking into consideration the prescribed warning related with checking the pipe wall thickness.

Safety wise, with LPG I would choose wet blasting.

You never know if removing some paint or sealant will result in leakage.

With wet you may also see bubbles and know to stop.

There is a wide range of abrasives for this process.

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All dry air/gas particle propelling systems, have a static risk.

This includes CO₂ - meaning earthing is important, and earth continuity in the work piece/s, must be checked. Then, as they say "As long as both the blasting unit and the piece you are blasting is properly grounded, you are unlikely to have static discharge problems."

CO₂ is obviously only suitable for well ventilated places and outdoor use.

Yes, wet sand blasting (3 sources for inputs: air + sand + water), that actually we use now at our plant to avoid spreading of dust of sand which is harmful to human when breathing its silica.

Thank you Abdel. It's nice to know someone appreciates my input.

Thank you Abdel halim and 34point5 for all these information will go ahead with wet blasting, it is interested subject.