Grooved vs Threaded Fittings

[964]

All,

My experience in fire protection has been limited to the contractor side, and I was always taught to use grooved fittings whenever possible. The benefits as explained to me always made sense, prefabrication, less labor for installation, lower overall cost, etc.

I continually see project specifications that require threaded fittings on all piping 2" or smaller. I have never heard a pro threaded argument, just grumblings from my coworkers and supervisors that the design engineer is old fashioned and driving the project cost up.

I have tried googling the topic, but only seem to find sales literature from grooved fitting suppliers singing the praises of their products. Can anyone here offer any insight on this? Or is it really just a matter of "We have done it this way for the past XX years and we aren't going to change it now."?

The only benefit I could think of would be the ability to reduce branch line sizes at every head with the proper size reducing tee. My current employer does not keep an extensive stock of threaded reducing tees, and they may be on back order. In addition we like to use a single size pipe for branch lines to reduce the variety of sizes that need to be handled during prefabrication in the shop. K.I.S.S. These two points make the idea a non-starter before I get into the cost-benefit analysis of using one size of SCH10 pipe vs more optimized sizes of SCH40 pipe.

When I was fresh out of school and working on boilers in power gen I thought all of the "Old Farts" were out of touch and I was going to change the world. Over time I learned that most of the decisions made by senior engineers were based on good reasons, and that those reasons held true through the years more than I originally thought. Looking back on it, I can really only think of one person I would put in the "Out of Touch Old Fart" category at this point, and my attitude has been tempered with time and a little bit of embarrassment.

Considering my limited view as a contractor, and only having been in this trade for a few years, I was wondering if this board could enlighten me on anything I may be overlooking. I am on my way to obtaining a PE license, and some day I may be writing specifications myself. With that in mind I really want to expand my product knowledge.

Huey

 

[OremusFire]

For me it depends on a lot of factors. Generally speaking if it's a tree system I'm designing with varying size of branchlines then I'll go threaded. If it's a larger system with all the branchlines being the same size all the way down then I go grooved. Sometimes ugly jobs that aren't all that accurate like retrofits I'll go threaded because they're going to be doing a lot of cut to fit anyways and they use the same machine for the cutting and threading. If I'm up in the air about it I'll see what the foreman or project manager wants - let them chew on it a bit and get back to me.

Of course different companies have their own way of doing things. I like to get the guys in and out even if that means going a little heavy on the material costs but to each his own.

 

[MGXFP]

It is easier to change threaded pipe than grooved. Grooved pipe needs to be run in long lengths without too many changes in directions to be economical to install.

In large, open areas I will use grooved S10 pipe and small offices with many offsets around HVAC etc I will use S40 thread pipe.

 

[DavidCR]

I suppose that it is because it is easy and cheap to get leak tight threads on 1.5" or less, and on small sizes in general the amount of joints tend to multiply.