# Stainless steel pipe: tape or compound? (need answer kinda quick) **URL:** \ **Category:** In My Humble Opinion\ **Created:** [May 26, 2015, 1:11pm UTC](https://boards.straightdope.com/t/stainless-steel-pipe-tape-or-compound-need-answer-kinda-quick/720874 "2015-05-26T13:11:18Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![Amateur\_Barbarian](https://avatars.discourse-cdn.com/v4/letter/a/59ef9b/32.png) [@Amateur\_Barbarian](https://boards.straightdope.com/u/Amateur_Barbarian)\ **Post date:** [May 26, 2015, 1:11pm UTC](https://boards.straightdope.com/t/stainless-steel-pipe-tape-or-compound-need-answer-kinda-quick/720874/1 "2015-05-26T13:11:18Z")
I have to assemble a new well pressure tank assembly today or tomorrow. (Bladder failed on the old one.) I got the piping assembly from an excellent online supplier (had every last bit and part, all best quality, for an absurdly low price)… and they included both a full roll of stainless steel PTFE tape AND a tube of pipe compound. I haven’t used anything but tape for many years, and AFAICT ss-grade tape is all that’s needed. From an HDPE (flexible plastic) well pipe to a male copper house-water attachment, with six or eight various stainless-to-stainless NPT connections in the middle… is there anywhere I should use compound instead of tape? Contestants have until I get back from HFT with a next-bigger crescent wrench (amazingly never having needed anything bigger than a 10" in all these years) to come up with the winning answer. PS - yes, I’ve checked the supplier site and asked them in email… but it’s been a three-day weekend. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [May 26, 2015, 1:13pm UTC](https://boards.straightdope.com/t/stainless-steel-pipe-tape-or-compound-need-answer-kinda-quick/720874/2 "2015-05-26T13:13:53Z")
I shouldn’t think so. I hate putting plastic over metal, I tend to tighten too much and crack it. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [May 26, 2015, 1:24pm UTC](https://boards.straightdope.com/t/stainless-steel-pipe-tape-or-compound-need-answer-kinda-quick/720874/3 "2015-05-26T13:24:46Z")
Stainless-on-stainless tends to gall unless lubricated. I recommend using tape and compound on those joints; the tape seals the big gaps, and the compound seals the tiny gaps AND lubricates the threads to prevent galling. ---
**Author:** ![Amateur\_Barbarian](https://avatars.discourse-cdn.com/v4/letter/a/59ef9b/32.png) [@Amateur\_Barbarian](https://boards.straightdope.com/u/Amateur_Barbarian)\ **Post date:** [May 26, 2015, 1:38pm UTC](https://boards.straightdope.com/t/stainless-steel-pipe-tape-or-compound-need-answer-kinda-quick/720874/4 "2015-05-26T13:38:29Z")
Using both is pretty much a no-no, from my experience and a general survey of the discussion. If you aren’t using one right, using two won’t help anything. It is essential to use a sealant, and the correct kind, and correctly, especially on stainless… but AFAICT the tape will do just fine. The only thing I can think of is that the copper-ss junction might be better served by compound. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [May 26, 2015, 1:39pm UTC](https://boards.straightdope.com/t/stainless-steel-pipe-tape-or-compound-need-answer-kinda-quick/720874/5 "2015-05-26T13:39:14Z")
I defer to some one with more experience than I. 🙂 ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [May 26, 2015, 2:51pm UTC](https://boards.straightdope.com/t/stainless-steel-pipe-tape-or-compound-need-answer-kinda-quick/720874/6 "2015-05-26T14:51:00Z")
> [@Amateur\_Barbarian](#): > > Using both is pretty much a no-no, from my experience and a general survey of the discussion. As a rank amateur, I’ve had nothing but success with this approach. Why is it frowned upon? ---
**Author:** ![Khendrask](https://avatars.discourse-cdn.com/v4/letter/k/3e96dc/32.png) [@Khendrask](https://boards.straightdope.com/u/Khendrask)\ **Post date:** [May 26, 2015, 4:04pm UTC](https://boards.straightdope.com/t/stainless-steel-pipe-tape-or-compound-need-answer-kinda-quick/720874/7 "2015-05-26T16:04:07Z")
I use PTFE tape only on water lines, and pipe dope only on gas lines. ---
**Author:** ![HoneyBadgerDC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/honeybadgerdc/32/1033_2.png) [@HoneyBadgerDC](https://boards.straightdope.com/u/HoneyBadgerDC)\ **Post date:** [May 26, 2015, 4:20pm UTC](https://boards.straightdope.com/t/stainless-steel-pipe-tape-or-compound-need-answer-kinda-quick/720874/8 "2015-05-26T16:20:46Z")
I use compound on most things now. Tape I use with stainless if I notice that non smooth feeling when I am pulling it tight. The threads are not always cut the same. I usually start off with compound and if it feels nice and smooth I will stay with it. ---
**Author:** ![LH75](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lh75/32/4438_2.png) [@LH75](https://boards.straightdope.com/u/LH75)\ **Post date:** [May 26, 2015, 4:22pm UTC](https://boards.straightdope.com/t/stainless-steel-pipe-tape-or-compound-need-answer-kinda-quick/720874/9 "2015-05-26T16:22:03Z")
Our Fire Sprinkler Fitters use both tape and compound on every threaded joint ---
**Author:** ![Amateur\_Barbarian](https://avatars.discourse-cdn.com/v4/letter/a/59ef9b/32.png) [@Amateur\_Barbarian](https://boards.straightdope.com/u/Amateur_Barbarian)\ **Post date:** [May 26, 2015, 11:20pm UTC](https://boards.straightdope.com/t/stainless-steel-pipe-tape-or-compound-need-answer-kinda-quick/720874/10 "2015-05-26T23:20:20Z")
> [@Machine\_Elf](#): > > As a rank amateur, I’ve had nothing but success with this approach. Why is it frowned upon? Dunno. But those who oppose do so vehemently. I’ve always had very good luck with tape - especially when using the quality stuff, not the tissue-paper white stuff that’s $1 a roll - so I’ve used ss/gray tape on the major joints where I can crank them together well. Might use compound only on the copper-ss joint, and a combination on the o-ringed union joint. Probably tape on the four small fittings. Reports as they happen. 🙂 ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [May 27, 2015, 1:02am UTC](https://boards.straightdope.com/t/stainless-steel-pipe-tape-or-compound-need-answer-kinda-quick/720874/11 "2015-05-27T01:02:35Z")
> [@Amateur\_Barbarian](#): > > Reports as they happen. 🙂 “A mysterious explosion at F.O.S.O.N.E. tonight…” 🙂 ---
**Author:** ![enipla](https://avatars.discourse-cdn.com/v4/letter/e/54ee81/32.png) [@enipla](https://boards.straightdope.com/u/enipla)\ **Post date:** [May 27, 2015, 1:26am UTC](https://boards.straightdope.com/t/stainless-steel-pipe-tape-or-compound-need-answer-kinda-quick/720874/12 "2015-05-27T01:26:52Z")
Stainless Steel pipe and fittings? For a domestic pressure tank? Is this something new, I’ve never seen that. ---
**Author:** ![Amateur\_Barbarian](https://avatars.discourse-cdn.com/v4/letter/a/59ef9b/32.png) [@Amateur\_Barbarian](https://boards.straightdope.com/u/Amateur_Barbarian)\ **Post date:** [May 27, 2015, 2:54am UTC](https://boards.straightdope.com/t/stainless-steel-pipe-tape-or-compound-need-answer-kinda-quick/720874/13 "2015-05-27T02:54:32Z")
> [@enipla](#): > > Stainless Steel pipe and fittings? For a domestic pressure tank? > > Is this something new, I’ve never seen that. Stainless is always a good idea for plumbing… just too expensive for most jobs. But it looks as if brass has been deprecated to lowball jobs for this purpose. Especially as the brass set that’s less than 13 years old is in pretty bad shape… mildly acidic ground water will do that. ---
**Author:** ![Amateur\_Barbarian](https://avatars.discourse-cdn.com/v4/letter/a/59ef9b/32.png) [@Amateur\_Barbarian](https://boards.straightdope.com/u/Amateur_Barbarian)\ **Post date:** [May 27, 2015, 5:06pm UTC](https://boards.straightdope.com/t/stainless-steel-pipe-tape-or-compound-need-answer-kinda-quick/720874/14 "2015-05-27T17:06:48Z")
Job went perfectly, using the tape on everything and a bit of compound on the union joint mating surfaces. Well, I have one stupid leak, right at the tank junction. I tightened it in place and will wait to see if it self-seals from the water minerals. If not, I have to dump the water, disconnect the union and re-do that joint from scratch. Even the copper into the brass valve was in great shape. I did NOT want to have to do any copper work. Had one of those serious OMFG moments, though. If you’ve never seen a pressure tank ‘apparatus,’ it’s about a foot of 1-inch pipe and fittings that probably couldn’t be hurt by leaving it on the highway for a week. So when I was disconnecting the incoming water pipe and the massive backflow preventer _broke off in my hand_, I had to sit for a few minutes and collect my wits. (Not that that’s a onerous job.) The brass was so corroded internally that the piece snapped off like a rotten branch. I have been mistaken for the Hulk in dim light but I could have broken this sweeping around it. Like breaking a breadstick. Then, when I was disconnecting the copper-line side, the valve broke off from that side with only a little more pressure. We were no more than a year from a major flooding break, maybe “any day now.” And THAT’S why you use stainless in these installations, kids. And THAT’S why you spend four whole bucks more for a pressure switch that cuts off if there is no system pressure. (You use an override switch to prime things if needed.) And THAT’S why the next project, new stainless and safety pressure valve and all, is an automatic sump pump in the berm I built around the water gear when we bought the house. It may never run, but I will sleep a whole hell of a lot better.