Restraint at Tee, Branch valve closed

[BernieH]

I'm considering the case of thrust restraint near a tee, where the branch valve is closed, the branch is pressurized and the run is not (see attachment). DIPRA covers this situation in their FAQ's at

http://www.dipra.org/faq/thrust.cfm

They say that the pipline on the unpressurized side of the valve can be used to act as a compression thrust block. But this method of restraint should be used with extreme caution. What could be done to eliminate the need for extreme caution? Can I simply ensure "run" in my example is fully restrained?
Thanks

" If the pressure is on the "branch" side of the valve, the thrust force will be balanced only by the frictional resistance along the branch. In other words, it should be treated as a dead end for calculation of the required length of restraint. ...In the above configurations where the situation is being treated as a dead end, consideration could be given to the use of the pipeline on the unpressurized side of the valve to act as a compression thrust block to restrain the thrust force against the valve. However, due to the expansion and contraction available with typical restrained joints, the possibility of excessive pipe movement might exist. Therefore, this method of restraint should be used with extreme caution."

 

[bimr]

Pipe and fittings are most often joined with push?on or mechanical joints. Neither of these joints provides significant restraint against longitudinal separation other than the friction between the gasket and the plain end of the pipe or fitting. Tests have shown that this frictional resistance in the joint is unpredictable, varying widely with installation conditions and other factors that are insignificant in other respects. Thus, these joints must be considered as offering no longitudinal restraint for design purposes.

Since the act of closing an inline valve creates a dead-end, valves not connected to other fittings require thrust blocks.

 

[rconner]

The use of "compressive strength of the unpressurized piping" might not be most applicable to your specific tee branch valve situation. That phrase is probably mostly referring to small diameter mainline shut-off valves, wherever they mighy be in straight sections of piping, e.g. as discussed in a later FAQ on the same site, i.e. when restrained or even unrestrained smaller diameter DIP is installed straight and tight on both sides of a valve or reducer, the compressive strength of some downstream piping and joints will likely carry the thrust. In other words ductile iron pipe and joints in basically straight alignment normally have substantial strength in compression, without necessarily having to rely on restrained joints off small valve locations.
If your tee branch valve is instead large and with pressure only on the branch piping, it would make sense to either install restrained joint piping for adequate length of branch and also effectively "extend" (i.e. stretch) all those joints in original installation, or instead to thrust block behind the tee etc.