Standards for Flushing Old Piping

Is the piping material specification correct? Has 'new pipe' been specified?

Why is the contractor installing rusty pipe? If your specification was done correctly, you should have specified the type of pipe to be used. If that is the case, make the contractor rip the rusty pipe out and put new stuff in.

...and point out that he won't get paid until he complies with the specification.

zhoucwi

I have hung pipe for a lot of consultants and end users. It is almost always the case that the specifications I work to are provided up front even if I have to do it personally so that we and the client are working towards a common end product. Was the issue of rusty pipe addressed during construction with the contractor. I assume pre-injection filtration is provided? When you say the installed pipe is pretty rusty are you looking at the exterior of the pipe and extrapolating internal conditions or was this an internal inspection. There are a variety of ways to clean suspect pipe depending on the degree of rust / scaling and likely mobility of foreign material in the pipe.

thks for all... good comments and suggestions.

we had a consortium with the contractor, though it's clearly the contractor's responsibility to clean up the pipes (the pipes are inside rusted), the enduser is not clear and always ask us (the equipment supplier) to clean up because we are part of consortium... though we had pointed out the the customer several times and even sent a letter to them that no warranty for problems caused by rust... now we are the only party to worry...

have you gents meet such enduser before that they don't care about their future operation? i had a meeting with the senior mangement of the customer, hope he pays more attention.

At the first place rusty pipes are not acceptable.

As already pointed out by others, if rust is only outside, it can be cured using rust removal chemicals followed by painting etc. There is no word IMPOSSIBLE, however inside rust removal is not a easy and one should give a thought to the risks associated with it :

1. It is difficult to check whether 100% rust is removed after flushing or not.

2. If any rust remains it could continue the rusting process in future leading to unwarned failure that could cause disaster.

3. Burst strength of the pipe material is already reduced for rusty pipe and continues if at some portion remains uncleaned from inside or outside.

Why should pay for rusty pipes?

Limbkar

The process we use is disconnect piping from engine, temporary with hose connect one to the pump the other end goes to 200 l. thank, connect suction end of pipe to the thank 600 mm. from bottom fill tank with water add comical bring water temperature at apr. 60c or better, circulate for few hours, when done drain all water and do another flash with clean water. Reconnect piping to the engine and make sure you insert strainer in the piping on inlet side of engine, run your tests on the engine, after done remove strainer and you should be ready to go.

One thing if you are using heat exchanger bypass it during flashing, same would go for Rads and Emot valve if used and all valves should be fully open.

How clean does it need to be? Clean-up procedures well understood--but to what spec? I.E. 'Seal-oil' cleanliness level means a) water flush to remove debris, then chemical clean to remove oil and grease, then acid clean to remove any rust or scale, then pickling with phosphate solution to form rust/corrosion barrier layer. Finally followed by clean water flush, air blow, then drying with hot air/nitrogen.

Much more stringent cleanliness levels for chemicals used in semi-conductor mfg. If you ever get it 'dirty' never can get it clean enough again.