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Pipe Support Painting System

Pipe Support Painting System

Pipe Support Painting System

(OP)
In one of our projects, there is not any clear explanation on the standard drawings for pipe supports, regarding painting. There is a FEED document covering shop and field painting specification of all fabricated items, but with regard to pipe supports it is only said that their color shall be similar to nearby structure, but no specified painting system (i.e. type and thickness of dry films in primer, intermediate and top coat).
What is your experience in this regard?
Do the "pipe supports" shall have structural steel painting system number, or they should assign to the attaching piping painting system number?
Why (as it is specified for pipes in the line list) there isn't a column in support list to have painting system specified for each support?
Any help will be highly appreciated.

RE: Pipe Support Painting System

Pipe supports are normally a structural item thus usually covered under the structural steel fabrication and painting specs. Offshore, pipe supports often have special requirements, or will at least have a more stringent painting & coating spec than what you might typically see onshore.

Learn from the mistakes of others. You don't have time to make them all yourself.

RE: Pipe Support Painting System

We distinguish between pipe supports and "secondary steel". Secondary steel is the extra steel added to the main structure, often field-designed and fabricated, to hang items like pipe, cable tray etc. and is given a surface tolerant coating system similar to the main structure, unless it is very small stuff (pregalvanized Unistrut etc.). Pipe supports themselves (shoes or more complex sliding or spring supports etc.) are bolted to secondary steel generally and are either galvanized (if temperature permits) or painted with a paint system acceptable for direct contact with the pipe. For hot pipe, most of that support is buried under the insulation and cladding so the conditions are very different than those the main structure will encounter in service and more akin to what the pipe itself experiences.

RE: Pipe Support Painting System

(OP)
Thank you for your reply.
to moltenmetal:
So, where these differentiating coating shall be specified. On the standard support drawings or it is better to assign a predefined painting system number in the support list?

RE: Pipe Support Painting System

I'd put the paint requirements in the Structural "General Notes - Coatings"; and then add to the pipe drawings any modifications to the general requirements [usually this involves very high temperature pipes]

RE: Pipe Support Painting System

MeDermott, No reason why a note on the drawing would not work, unless you have a 10 page long + paint specification, in which case referencing the spec number would be far more efficient.

Learn from the mistakes of others. You don't have time to make them all yourself.

RE: Pipe Support Painting System

Here is the expensive alternative ....

In the Norwegian sector of the North Sea, stainless steel is the norm for supports offshore, and in some cases, duplex stainless has been specified. These are mostly horribly costly thin wall square hollow sections, which create their own joint detailing problems.

The reason .... you don't have to paint stainless supports and over a lifetime, it's said to be cost effctive.

RE: Pipe Support Painting System

Just a little reminder about spring hangers....

Be aware that the spring itself needs a special coating, which must accommodate deflection ...this is typically neoprene.

For extreme corrosive conditions, sometimes the entire spring hanger is hot dip galvanized, including the spring

MJCronin
Sr. Process Engineer

RE: Pipe Support Painting System

I would recommend you to be careful with high temperature piping with hot deep galvanized equipment attached on carbon steel pipe. The following may give you an inside on the zinc embrittlement effect on the carbon steel structural member/pipe at high temperature applications:

http://www.scielo.br/scielo.php?script=sci_arttext...

As far as I remember Australian Standard 4041 (Piping) recommend not to use zinc coating on the pipe or on equipment attached to the pipe beyond 250 deg C (not exactly sure about this temperature but it is not too high) due to the embrittlement. Therefore I would recommend you to select aluminium based coating instead of galvanizing for this type applications.

RE: Pipe Support Painting System

We limit galvanized components to 400 F, whether on their own or in contact with pipe, whether carbon or stainless.

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