Can I use standard ABS drain pipe to connect hose to holding tank??

[Davemwd]

Greetings,

I'm plumbing my new holding tank and was wondering if there are any disadvantages to using standard ABS drain pipe fittings as pictured. The old tank had 90 degree hose barb fittings which were plugged when I pulled the tank. I thought this set up would lessen that chance- but being new, I don't know if this is a "no-no" or not. The pipe would be used strictly for the 90 degree turn (as shown) , a barbed fitting will be installed and connected to new Saniflex. Thanks!

 

[Comodave]

I am not a plumber but when people use hard pipe as a discharge they usually use PVC.

 

[psneeld]

Through the years, large deviations in direction of piping aboard small vessels were usually flex fittings while straight runs might be well supported hard piping. This was done for vibration and pounding concerns.

No matter what used, no sharp bends or 90 degree fittings. Probably one reason why "sanitary" tee fittings are made.

Not saying the ABS shouldn't be OK. If proceeding, use the heavier schedule at the bends. Also make sure of excellent glued and supported fittings.

 

[Bacchus]

My previous boat had a large area but shallow holding tank that sat on a platform. When pumping out it always left 1-1/2" of " waste" in the tank because as soon as that level was reached the vacuum drew air and pumping ceased.
When reworking the system I added a PVC trap to the tank before the hose to deck fitting. The result was the ability to completely empty the tank.. especially helpful at end of season when I would stand on the gunnel and create enough list to make the trap the low side of the port to stbd oriented tank... worked great for 10+ years.

 

[psneeld]

Good point Don, I wound up doing the same.

 

[Bmarler]

Abs is a terrific choice for sewage, I think using a sweep 90 is also a good choice as it eliminates a hard corner. That’s a lot of elevation before the hose barb though, so you will want to make some kind of support so you don’t accidentally knock that out of the tanks threads.
A sanitary t was mentioned before. That’s a shorter sweep with the advantage that you can use the other leg of the t for a clean out. Puts the hose barb much closer to the tank and less likely to be damaged by a sudden blow.

 

[luna]

Not saying the ABS shouldn't be OK. If proceeding, use the heavier schedule at the bends. Also make sure of excellent glued and supported fittings.

ABS is used almost exclusively in Drain, Waste and Vent applications and I don't see any reason why it would not be suitable in this instance provided the piping has no fluids that remain in it (never a good thing) and everything is well supported/protected.
Being a DWV pipe that is not designed to be under any mechanically induced pressure, I don't think there are any heavier schedules in ABS. It is what it is.
Please let me know if you find anything heavier.

 

[psneeld]

ABS is used almost exclusively in Drain, Waste and Vent applications and I don't see any reason why it would not be suitable in this instance provided the piping has no fluids that remain in it (never a good thing) and everything is well supported/protected.
Being a DWV pipe that is not designed to be under any mechanically induced pressure, I don't think there are any heavier schedules in ABS. It is what it is.
Please let me know if you find anything heavier.

May not be readily available, but have seen ads for 40 or 80 schedule.

I mention that it may be OK, not that ABS is unsuitable for sewage, just this application of a large 90 degree plumbing set up on only plastic threads in a "motion" environment. Plus it is under slight vacuum when pumping out, probably minor pressure until there is a blockage.

Google -
Schedule 40 and Schedule 80 ABS pipes differ primarily in wall thickness and pressure rating:

• Wall Thickness: Schedule 80 pipes have a thicker wall compared to Schedule 40 pipes, making them more robust and able to handle higher pressure and heavier loads4.

As far as exclusively used - and other sites recommend PVC in many applications.

"Before you put too much thought into deciding between ABS and PVC plastic piping, you should know that your local government may have already made the decision for you. Some local building codes mandate the use of one type of pipe over the other for drainage, sewage, or other plumbing projects, though many leave the option up to plumbers and builders."

What’s the Difference Between ABS and PVC Pipe?

Knowing which plastic piping to use for your plumb

www.benjaminfranklinplumbing.com

 

[luna]

I agree, any plastic piping needs suitable support/protection. I also agree that if there is a heavier version of ABS produced and available I would use it. I just don't think it exists.

So, Google says Schedule 40 ABS differs from Schedule 8o in wall thickness and pressure rating.
Google as far as I know does not make pipe.

What does the Industry that produces ABS piping say? Do you have a manufacturer of this Schedule 80 ABS?

 

[psneeld]

Seems 40/80 is available at Home Depot and Lowes if online ordered.

VENTRAL 2 in. x 8 ft. Industrial Grade Schedule 80 PVC Pressure Pipe PI000-43-08-2080-001 - The Home Depot

Add length to an existing piece of your pipeline by choosing Industrial Grade Schedule Pressure Pipe VENTRAL.

www.homedepot.com

2 in. x 8 ft. Industrial Grade Schedule 80 PVC Pressure Pipe​

 

[rslifkin]

I didn't do the trap setup, but I did a dip tube for mine (made from schedule 40 PVC). The tank sits on a slight angle towards the dip tube, and I placed the tube very close to the bottom of the tank so it starts sucking air with about 1/2" left, but will pull a little more out if you let it keep sucking. The gallon or so of waste left behind isn't a big deal in a 70 gallon tank.

 

[luna]

Seems 40/80 is available at Home Depot and Lowes if online ordered.

VENTRAL 2 in. x 8 ft. Industrial Grade Schedule 80 PVC Pressure Pipe PI000-43-08-2080-001 - The Home Depot

Add length to an existing piece of your pipeline by choosing Industrial Grade Schedule Pressure Pipe VENTRAL.

www.homedepot.com

2 in. x 8 ft. Industrial Grade Schedule 80 PVC Pressure Pipe​

And there I thought we were talking about ABS, the black DVW pipe as shown in the OP's picture, not PVC pipe.

 

[Wtrguy]

In my experience with residential plumbing, ABS is used inside the residence, PVC is used for any buried applications. I would have no issues using ABS. And tees are the norm vs. 90's for the additional cleanout they provide.

 

[psneeld]

And there I thought we were talking about ABS, the black DVW pipe as shown in the OP's picture, not PVC pipe.

Sorry, searched for ABS and this snuck in when I hit the button.

This discusses it.... ABS Pipe Sizes & Dimensions For Schedule 40 and 80

You may be right, I have seen references but I don't seem to see a viable supplier for it.

If doing the project with the large amount of fittings, I would go PVC 80 then.

 

[Diep]

I think ABS DWV pipe would be fine. You can also consider PVC but I don't see any need to go beyond Schedule 40 if you do.

Unless you are trying to hit that elevation for a reason, I would bring that 90 as close to the tank as possible using the parts you have.

If you're still brainstorming, I would consider a sanitary tee with a cap. This will shrink the fittings down and still allow you to service the bend if an issue arises. You also might consider the same thing with a sanitary wye. If you are tying a hose in here it will allow the hose to sweep down to the fitting rather than run in level.

Whatever you do, look to support or protect the fittings so they can't be busted off at the top of the tank.

In general I think using ABS or PVC in place of hose is a great idea in areas it makes sense.

 

[NoRain]

My previous boat had a large area but shallow holding tank that sat on a platform. When pumping out it always left 1-1/2" of " waste" in the tank because as soon as that level was reached the vacuum drew air and pumping ceased.
When reworking the system I added a PVC trap to the tank before the hose to deck fitting. The result was the ability to completely empty the tank.. especially helpful at end of season when I would stand on the gunnel and create enough list to make the trap the low side of the port to stbd oriented tank... worked great for 10+ years.

That.is.Brilliant!

 

[Nordlund Xpress]

95% of our head plumbing from toilet, to tank to discharge - all straight runs and turns in PVC, all the way to the discharge pumps, in our Nordlund. No leaks, smells or plug ups. We're sold. Nordlund did a nice job of supporting the PVC to the hull with clamps and rubber pads - secured about every 12". When we were up at the yard I confirmed that has been their standard design install for years.

 

[Davemwd]

Great responses! Thank you! I'm intrigued by the install of the trap - I'm trying to figure out how that works- The trap holds liquid in the "U" when you apply vacuum wouldn't that just suck out the water in the U and then proceed to suck out the tank until you reach air? (I'm assuming the trap is level to or above the tank- I can see this working if the trap is level to the bottom or below the tank) all my fittings are on top of the tank.

 

[Davemwd]

I think ABS DWV pipe would be fine. You can also consider PVC but I don't see any need to go beyond Schedule 40 if you do.

Unless you are trying to hit that elevation for a reason, I would bring that 90 as close to the tank as possible using the parts you have.

If you're still brainstorming, I would consider a sanitary tee with a cap. This will shrink the fittings down and still allow you to service the bend if an issue arises. You also might consider the same thing with a sanitary wye. If you are tying a hose in here it will allow the hose to sweep down to the fitting rather than run in level.

Whatever you do, look to support or protect the fittings so they can't be busted off at the top of the tank.

In general I think using ABS or PVC in place of hose is a great idea in areas it makes sense.

Great suggestions! thanks, I will use the Y's instead of the 90's. I will be shortening the hight of the pipping - I just threw those pieces together for a pic.

 

[DDW]

I've used a lot of Sch 80 PVC for wast plumbing on a boat. It is stronger than ABS drain for sure. The ABS might be good enough, but the consequences of failure are not a thing I'd want to contemplate in that application...

 

[psneeld]

Great responses! Thank you! I'm intrigued by the install of the trap - I'm trying to figure out how that works- The trap holds liquid in the "U" when you apply vacuum wouldn't that just suck out the water in the U and then proceed to suck out the tank until you reach air? (I'm assuming the trap is level to or above the tank- I can see this working if the trap is level to the bottom or below the tank) all my fittings are on top of the tank.

My p trap was below the tank so the tank would keep draining and the pump keep building a small vacuum.

 

[psneeld]

Haven't found an internet source, but AI search engines seem to think there is a schedule 80 ABS pipe. But even their sources seem to cover the schedule dimensions but fall short of making it clear that someone actually sells or uses the stuff.

"Yes​

Yes, there is a Schedule 80 ABS pipe. ABS pipes are available in both Schedule 40 and Schedule 80 dimensions, making them suitable for various applications, including industrial and high-pressure systems1. Schedule 80 pipes have thicker walls compared to Schedule 40, providing higher pressure resistance and durability"

 

[DDW]

I have seen Sch 80 ABS, but not in the drain sizes. DWV ABS that you get at Home Depot is actually foamed ABS, to make it lighter (and cheaper). It doesn't need to be very strong or hold much pressure. Nor does it in a boat waste application, other than physical damage - but you aren't burying it in dirt or enclosing it in sheet rock.

 

[Davemwd]

I have seen Sch 80 ABS, but not in the drain sizes. DWV ABS that you get at Home Depot is actually foamed ABS, to make it lighter (and cheaper). It doesn't need to be very strong or hold much pressure. Nor does it in a boat waste application, other than physical damage - but you aren't burying it in dirt or enclosing it in sheet rock.

that's my thought- I plan on using some type of barrier (plywood wall) to protect the pipe - this will also give me a place to mount equipment

 

[Davemwd]

My p trap was below the tank so the tank would keep draining and the pump keep building a small vacuum.

That's what I thought- great design!

 

[Bacchus]

My p trap was below the tank so the tank would keep draining and the pump keep building a small vacuum.

Yes Ditto. My discharge was bottom of tank and allowed N early drying tank/ maintaing vacuum via pump out. Not applicable to dip tube set ups.

 

[SIBERNUT]

I note the suggestion of a sweep vs a hard 90. What the heck are you guys eating that wouldn't make it thru a 2"
90° bend ???!!! We talkin Guinness contender here ?

 

[Bmarler]

I note the suggestion of a sweep vs a hard 90. What the heck are you guys eating that wouldn't make it thru a 2"
90° bend ???!!! We talkin Guinness contender here ?

Lol, a hard 90 will have a sort of dead zone. A sweep will clear and self clean better. A hard 90 will also raise the amount of pressure it takes to push a slurry through it.
A hard 90 will work, but a sweep is better.

 

[psneeld]

I note the suggestion of a sweep vs a hard 90. What the heck are you guys eating that wouldn't make it thru a 2"
90° bend ???!!! We talkin Guinness contender here ?

It was never me or my traveling companion, but bring on a crew or passengers that may eat and wipe different than your habits, and you may want a 747 turbine engine for a macerator on your boat.

 

[SIBERNUT]

Eat more Mexican....