Serviceable Valves on Fuel Manifold?

[Arthurc]

Hi all, After a 1 year hiatus from boat projects I've got a long list before summer and starting to finally build my fuel manifold. I plan on tig welding stainless fittings for the manifold as it will eliminate most leak points and lead to a cleaner install. In terms of valves I've been wondering about using these serviceable stainless valves, big advantage I see is that I could take apart the valves and weld on the fittings then reassemble without risking any heat on the seals. Curious if anyone has experience with them.

https://www.amazon.com/DERNORD-Ball-Valve-Inch-Threaded/dp/B07DVNL865/ref=asc_df_B07DVNL865/?tag=hyprod-20&linkCode=df0&hvadid=242021983106&hvpos=&hvnetw=g&hvrand=16191253819334685760&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9033255&hvtargid=pla-473832637616&th=1

Thanks much.

AC

 

[O C Diver]

Suppose the valves have a problem after a year, how difficult will it be to switch to another model valve if they're welded on? I can accept welding up a manifold. Welding on the valves is just begging for a problem. The system might see 10 PSI. Use a top quality diesel compatible pipe dope and focus on something else.

Ted

 

[Arthurc]

That’s my concern, as far as a valve having an issue it would be easy to just stock a bunch of rebuild kits, but if these type of valves have design flaws it would be a real problem.
I’ve had limited luck and even heard yard folks say that truly getting leak proof diesel fittings is a nightmare. With this route my only connection points would be to the hoses or about 80% less total threaded unions.

I believe that loctite 565 combined with tape is suppose to be the best solution for where you do have threads.

 

[Datenight]

The Loctite alone is fine. Many recommend against using tape as it can cause problems if pieces get into the fuel stream.

Rob

 

[O C Diver]

That’s my concern, as far as a valve having an issue it would be easy to just stock a bunch of rebuild kits, but if these type of valves have design flaws it would be a real problem.
I’ve had limited luck and even heard yard folks say that truly getting leak proof diesel fittings is a nightmare. With this route my only connection points would be to the hoses or about 80% less total threaded unions.

I believe that loctite 565 combined with tape is suppose to be the best solution for where you do have threads.

So if one of the welded on flanges proves to be the issue (distorted from welding, a crack developes, a casting flaw, a scratch on the face for the seal), how much of a nightmare will it be to replace.

Don't use cheap Chinese junk fittings that aren't well machined and the risk of leaks is near zero with a quality pipe dope. Forget the tape. Assembly the manifold, plug all the outlets, and pressure test it before installing with 100 PSI of air pressure. Spray window cleaner on all the joints to look for leaks (window cleaner makes bubbles where there are air leaks).

Ted

 

[Comodave]

I have used gray Marine Tex to seal threads on permanent connections. Never had a leak. Clean the threads well with acetone before assembly. Also assemble it first to determine how many revolutions the fittings will have before they get tight and that they line up the way you want them to before using the Marine Tex. Picked this up on Tony Athens web site.

 

[Arthurc]

Agree on non-cheap fittings, I’ve had good luck with the Dickson brand stuff but still looking for the weld on version. Swaglok makes one as well.
I think that’s a really fair point on the valve assembly having an issue, it would be very easy to fix if it doesn’t pressure test right away, less so once installed. That said I could say the same thing about finding that a threaded connection in the middle of the manifold had an issue. One thing I could do is weld the manifold and 2” nipples onto each connection point which would space out the valves more and make it easier to replace later while still not fully welding the valve on.

AC

 

[O C Diver]

Agree on non-cheap fittings, I’ve had good luck with the Dickson brand stuff but still looking for the weld on version. Swaglok makes one as well.
I think that’s a really fair point on the valve assembly having an issue, it would be very easy to fix if it doesn’t pressure test right away, less so once installed. That said I could say the same thing about finding that a threaded connection in the middle of the manifold had an issue. One thing I could do is weld the manifold and 2” nipples onto each connection point which would space out the valves more and make it easier to replace later while still not fully welding the valve on.

AC

Welding on nipples and threading valves sounds a lot better. Before your start welding, play with valve spacing. It's very easy to not allow enough comfortable room for the handles on 1/4 turn ball valves. Also consider what would have to be done to replace a valve. While the handle can be removed, what will be involved in unscrewing the valve. In a perfect world, with enough play in the hoses, loosening or removing the mounting hardware should allow you to unscrew a valve. Engineering it well, usually guarantees trouble free performance.

Ted

 

[jleonard]

Use Rectorseal on the threads and they will not leak. I've made many, many threaded connections for fuel and never had one leak.

 

[Arthurc]

Great point, I’d like to cut some nice mounting tabs and weld them into the manifold so it sits off the starboard backing at least 1” so the valve can rotate freely. Although this is one reason I liked the 3 piece valves as it’s much easier to replace valve parts, I guess it’s a trade off versus the likelihood the welding causes issues. I ordered 2 Dixon ones I finally found and am going to make a test piece and pressure test it before I make a final decision or big part order. I’m still curious if those 3 piece valves have downsides other than cost, with companies like Dixon and swaglok making them?

 

[Comodave]

One thing to think about if you are really concerned about leaks is that these valves have 2 additional points of possible leaks at the seals on each end.

 

[Arthurc]

That’s my concern with these valves for sure, the advantage and maybe I’m not thinking about this correctly us to get the valves all perfectly positioned when you have a bunch of screw fittings often means some are slightly under tightened and maybe some over, felt like welding was a clean way to address it but I may just be going with the skill I know versus the one I don’t have much experience in.

 

[twistedtree]

Welding on nipples and threading valves sounds a lot better. Before your start welding, play with valve spacing. It's very easy to not allow enough comfortable room for the handles on 1/4 turn ball valves. Also consider what would have to be done to replace a valve. While the handle can be removed, what will be involved in unscrewing the valve. In a perfect world, with enough play in the hoses, loosening or removing the mounting hardware should allow you to unscrew a valve. Engineering it well, usually guarantees trouble free performance.

Ted

The manifolds I've seen are made using nipples like this. The only suggestion I would have is once welded together, run a tap over the threads to be sure they are good. It doesn't take much distortion to create leaks.

 

[O C Diver]

The manifolds I've seen are made using nipples like this. The only suggestion I would have is once welded together, run a tap over the threads to be sure they are good. It doesn't take much distortion to create leaks.

Agreed!

Also use nipples that have a hex wrench fitting in the middle. You should be able to put open ended or tubing wrenches on both the valve and the nipple for assembly and disassembly.

Ted

 

[Arthurc]

Good call Ted, I've ordered a bunch of stuff to play with and will report back. Now placing an order for nipples with hex fittings

 

[C lectric]

I have made manifolds for water typially under 100+ PSI.
I always used a hydr. coupling with wrench flats or a good weld. Much heavier walls OR the weld on fitting with a flat flange specifically for welding.
Once the cplg. was in place I then used a nipple again with the wrench flats.

I did not use Tape , rather either Rectorseal 5 , Loctite 567 or Aviation Form A Gasket.

Although not a hydr. mechanic I have experience with tape in hydraulic systems and do not wish to repeat them.

 

[FF]

On the bottom of the fuel tank a valve with a pull to shut off cable run to the outside of the boat is simple to arrange.

It can stop a fire or a thief .

In other locations the dirt house folks have fuel valves that close automatically in the event of a fire.
Again really cheep insurance.

 

[TJM]

I would never make my own manifolds and I am a Navy Nuclear welding Engineer.
They are easy enough to purchase with excellent quality. In the past year I have installed 3 new Diesel manifolds purchased from KTI fuel systems. Mix and match the number of inlets, ball valves and where you want the holes to be. Used Loctite 592 and I have no leaks. I never use thread tape on a boat, there will be some that have gotten away with it, but not me.
As far as welding ? If the alloy is 304 SS, be sure to use 304L weld wire and just so you know, post welding you will have lost your passive layer in the heat affected zone and it will convert to a little iron oxide staining and turn orange.

 

[Arthurc]

I’ll checkout KTI.
As far as welding stainless you can use 308 too which is what I use mostly, and you are absolutely right about the oxide layer although I added a tigbrush to my shop last year which is super awesome, basically it uses acid + charge to rebuild the layer, you just brush it over the past and it instantly becomes silver again. I did some stuff on the exterior of the boat over a year ago and zero rust spots, when I use to use a wire brush it was never perfect.

 

[Barking Sands]

My own personal opinion. If I were making a manifold and I was concerned about valve replacement I would use welded JIC 37 degree fittings either male or female welded to the manifold. I would then use threaded fittings to go into the valve. On the opposite side of the valve I would use the opposite fitting (male/female) JIC fittings. This makes it slightly easier to pull the valve out when changing one using just the JIC male/female couplings. In addition you can premake 2 or 3 valve that have the fittings on them so when the need arises you loosen the JIC compression fittings on either side of the valve, swap out for the new premade valve and just tighten the fittings. I will be doing the same for my electric inline fuel pump so if I need to swap out a failed lift pump it will just be 2 JIC couplings and one premade electric plug. Should be able to swap out in under 10 minutes even in poor conditions using 1 wrench.

37 degree JIC fittings are industry standard on many aircraft with systems operating from 3000-3200 psi. And if they get damaged on the critical mating surface after being removed dozens and dozens of time you can use a soft copper seal that goes by several names such as SECO. They work GREAT. Link below.


https://www.hydraulicsdirect.com/Stainless-Weld-On-JIC-Male-Rigid-hose-fittings-p/ss-wo-mj.htm

https://www.amronintl.com/copper-conical-seal-12-jic-3-4-inch-25-per-roll-seco7c12-roll.html


I just redid my fuel systems and eliminated any hose/clamp and compression ferrule/olive style fittings (hate those fittings) in favor of 37 degree copper JIC.