Regarding installation temperature, can anybody explain what is the preferred practice to determine it?

The plant will be built in March when the ambient temperature is likely around 10 degree C. The piping material is A333 Gr 6 since the ambient temperature can drop down to -40 C in winter. There might be shut down for maintenance during winter time and the temperature with insulation on piping hopefully drops to -20 C. Design temp is 150 C.

Given the situation, what installation temperature should I take? -40 C is blamed by my fellows for being too much conservative. 10 C seems to be too high. Can I take -20 C as an installation temp since maintenance and start-up is another installation process (from shrinkage to expansion)?

Many thanks in advance.

Hi Newpiper

In our usual practice we keep installation temperature as 10 deg C but check expansion stress for full range i.e. -40 deg C to + 150 deg C.
Changing installation temperature to -40 deg C will be quite conservative one & may create problem for nozzle load, while stress range will be same as above.

Hello Shr,

I usually can check the stress for the full range -40 deg C to +50 deg C. but the problem is at nozzle and support loads. Usually the stresses are not a problem. The main concern is there is no clear cut to determine the installation temp and every time many engineers have different opinion.

In your idea, stress shall be check for full range while nozzle loads can be check against liberal case such as +10 deg C to +150 deg C, isn't it?

Shutdown-startup case is not considered in deciding the install temp?

Thanks,

The minimum install temperature of the plant should be defined by your DBM for the project or a company or client stress standard. Assuming you have checked there and it has not been defined I would choose the lowest possible temperature your pipe will be installed at.

The first step would be to find out if your piping is being installed in winter. If it is find out from the construction team at what temperature they will stop working at. One place to check would be OHS statutes in your juristiction. Some have minimum working temperatures, some companies also have minimum working temperatures. +10 would be overly liberal for your nozzle loads if the piping is being installed in a tank farm in the winter in Fort Mac.

I have always wondered if the install temperature makes a significant enough difference in the real world to worry about. If you have a 6m pipe the difference in length for a temperature from -20 to +10C is about 2mm. Meaning that the difference in expansion we are comparing is less then the construction tolerance of the person cutting the pipe. So if you have a modulerized project where everything is flanged and assembled in the field the effect of unplanned cold springs at the flange joints will be greater then the difference in install temperature and the unplanned cold spring is never really looked at in terms of nozzle loading. Is the change in install temperature a negliable effect compared to the rest of the margin or error in the work we do.

Thanks Greg F,

You pointed out another real issue, severity of install temp changes and construction errors.

Unfortunately, there is no technical people and reference data in client side. A project manager confirms that the installation will be done after March and construction team won’t bolt up interconnecting shop spools to modulized building tie-in points until ambient temp is around +10 which will be likely happing in late spring.

Just definition of install temp. Is it the temp of initial installation only?

I'd consider the installation temperature to be the temperature of the piping when the final closure weld is made for a section of piping between anchors or control points.

In terms of CAESAR II input, I consider the ambient temperature (installed temperature) to be the temperature when the pipe is cut AND the temperature when the final closure weld or flange connection is made.

It's a bit picky in light of all the fitup issues in the field but by addressing both temperatures (and I have no recommendation for when they differ) you will working with the right strain.