Chilled Water Hot Tap - Bolt-On Saddles

[getitdone91]

I’m trying to come to a conclusion on code requirements as they pertain to bolt-on gasketed saddles for hot tapping in a chilled water system. Ultimately, I’m questioning if they are allowed by code?

My present point of view:
From ASME B31.9-2008, 904.3.1:
…branch connections may be made by any of the following methods:
(a) Fittings. Tees, extruded outlets, laterals, crosses, etc., manufactured in accordance with a standard listed in Table 926.1.
(b) Outlet Fittings. Cast or forged, integrally reinforced, welding outlet fittings, nozzles, forged couplings, and similar items, attached to the main by welding.
(c) Direct Connection to the main. Welding the branch pipe directly to the main, with or without added reinforcement, as shown in details of branch connections in Figs. 927.4.6-1 and 927.4.6-2 and the rules of para. 904.3.2.
(d) Mechanically Formed Tee Connections in Copper Tube. See para. 930.2.

None of the bolt-on tapping fitting assemblies I’ve seen are manufactured to a standard listed in the referenced table. Therefore, my present conclusion is that these types of fittings do not meet code requirements.
Does anyone care to shed some light regarding the use of these fittings or code interpretation?

 

[dynamo78]

Just basing on my experience, this is allowed even on chiller condenser cooling tower piping.this is in the western pacific.
Verify your local R & R.

 

[EnergyProfessional]

you mean weldolets and threadolets in lieu of a Tee? Most specs require a Tee when the branch is more than 1/2 of the main pipe size.

 

[Compositepro]

Bolt on saddles would properly be called a cold tap rather than a hot tap.

 

[getitdone91]

@Compositepro: ok

@HerrKaLeun: I'm referring to bolt-on tap fittings rather than using a split tee or weldolet for a new branch connection.

 

[EnergyProfessional]

I had to look up what a bolt-on-tap is. It seems to rely on some gasket or seal? that would concern me if you keep it for long.
but it looks like hot-tap refers to the ability to tap into an operational pipe (as opposed to take out a piece and install a Tee). Hot doesn't mean welding or soldering.
At least this manufacturer refers to all as hot-tap

 

[getitdone91]

@HerrKaLeun: Right, it relies on a gasket to create a seal. Long term, a gasket will degrade to some extent, and then leaks will occur.
The question at hand is are these types of tap fittings allowed per code? And if they are, what standard should these fittings be manufactured too? Has anyone ever specified using these?

 

[EnergyProfessional]

Whether code allows them or not... they don't sound like a good idea on the long run. that would be my consideration.

I'm very conservative and only allow soldered or welded pipe and flanged valves etc. for welded pipe. All the vic-coupling, cramp-fitting etc. will fail over time. I don't even allow threaded pipe because of that (especially with glycol threads will leak). In theory with 100% good material and 100% perfect installation the above methods may not be that bad.

My employer has over hundred buildings. 2% probably have the above fittings (vic, cramp etc.) and 99% of leaks we have are from those 2%. Draw your own conclusions if a bolt-on-tap is a good idea for your client if they intent to keep the pipe beyond 5 years.

 

[DBronson]

getitdone91:

Hot tap fittings are mostly used on pressurized potable water mains. There are probably hundreds of thousands of these fittings in use around the world. Generally they are buried after the tap is made. The AWWA has standards that cover the deign and use of these. You could review those standards to see if they would apply to your situation. The local AHJ would have to agree. HerrKaLuen's points are well taken, but perhaps the saddle fittings could be used for a temporary fix and then swapped out for a more permanent solution when the CW system is next taken down for maintenance.

Regards,

DB

 

[EnergyProfessional]

AWWA may allow them. but you must know municipal water underground loses a few % due to leakage and that is accepted as long as it doesn't creates sinkholes in the street (which it sometimes does).

It sounds like the OP has a indoor application and i doubt the owners will like a few % of the flow rate coming out of that fitting. so the AWWA allowing it for outdoor underground municipal water (also not regulated by code) doesn't help him much.

 

[Wilbur55]

I also understand "hot tap" to mean making a connection to a pressurized line while the pressurized line remains in service. I have seen it used in reference to pipes conveying fluids that are not potable.

What the OP seems to be describing is a "mechanical tee."

https://www.grinnell.com/index.php?section=us-mech-3

They are often specified for fire sprinkler systems, so the reliability "should" be high.

He seems to say he is not referring to something like this:

http://www.furmanite.com/products/hot-tapping/hot-tapping-fittings/split-tee-hot-tap-fittings/

I have not seen specs where weld-o-lets are allowed for branch connections only up to half the size of the main. This manufacturer seems to accommodate full-size connections on 36" pipes:

http://www.bonneyforge.com/specs/branch/weldolet_szonsz.cfm

 

[getitdone91]

@DBronson: Thanks. I am familiar with the AWWA standards as they relate to tapping saddles. Like HerrKaLeun followed, they are typically used in an outdoor/underground potable water piping or other. I am questioning the use for an indoor building services application (data center type facility).

@Wilbur55: I am referring to a mechanical tee, similar to what you have posted in the first link; designs differ slightly, but principle is the same. Your following two post are something that I would typically specify for use.

Again, I'm trying to determine (by applicable codes) whether these mechanical tees/bolt on saddles are allowed for use in a chilled water application. The facility I'm working on sees them as an acceptable practice, mainly from the upfront cost and time savings for the install. From a mechanical engineering stand point, I don't see them as an appropriate solution for the long term and the imminent threat of leaking/failing. That's my opinion that I would like to support with a code backing.

 

[Wilbur55]

I haven't looked for code references, but codes prescribe a minimum standard. If there are economic reasons to exceed code requirements, then it is the call of whoever is paying for it whether they want to exceed the code-required minimum standard.

Depending on the sizes of the pipes and the locations of the connections, the economic justification of leak-avoidance may be less difficult for a data center than for other applications. Data centers get many fancy, added-cost features: generators, raised floors, clean agent fire protection, precision air-conditioning systems with redundancy, glycol loops, etc.

What is the cost of downtime in the data center? How does the probability of a leak in a mechanical joint compare with that for a welded joint?

Given the number of manufacturers who would lobby against a code prohibiting their product, and their accepted use in life-safety applications (wet fire sprinkler systems), I doubt there is a code that prohibits the use of mechanical joints in chilled water systems; or a code that fine-tunes the prohibition to say they are okay everywhere except data centers.

You might look for a best-practices document from a group that is especially interested in HVAC for data centers. They may have scary case studies to put in front of whoever needs to approve the cost difference between mechanical tees and welded joints. What do the suppliers of the computer room cooling units recommend -- and why?