Drum Trap Cover

[rdgallo]

I have an old cast iron drum trap that my tub drains into. It has a pot metal cap on it that corrodes through every two years. Do they make a stainless or plastic cap I could use instead of this pot metal one? If so, where can I purchase one?
Thanks, and Merry Christmas!!

[LazyPup]

As I am sure you have learned from experience, snaking a line with a drum trap is impossible, and cleaning a drum trap is a chore reserved only for a first year apprentice training exercise. For those reasons drum traps are no longer used so you may have a booger of a time finding a cap. The best solution would be to cut it out and install a PVC trap that wont corrode.

If you have metal pipes you could install the PVC trap and connect it to the metal pipes with a rubber FERNCO coupling.

The whole project would cost less than $20 and take under an hour to complete.

[HayZee518]

I have seen metal plugs with extremely built up lead at an extreme taper on the threads which should adapt to different sizes of traps and cleanouts. The lead is soft enough to form a seal.

[kactuskid]

Bare in mind that replacing a drum trap with a P trap may also require you to install a vent for your tub in the case you don't have one. You can accomplish this by installing an air admittance valve if they're approved for use in your area.

[LazyPup]

Removing the barrel trap and installing a P-trap should not necessitate any changes in venting. Venting is determined by the length of the waste arm and it is the same regardless of which type of trap was installed.

To be a bit more specific..The maximum vertical distance from the drain opening to the trap may not exceed 24" except on a washing machine standpipe.

There are tables in the code that list the maximum permissible horizontal length of the waste arm from the Trap weir(actual point of discharge in the trap) to the vent. The actual mathematical method of computing the length is by deviding the diameter of the waate arm line by the fraction of an inch pitch required. A tub requires an 1.5" trap, which is required to have a 1/4" per ft. pitch, thus the maximun lengt of the waste arm is 1.5/.25= 6ft. The code does allow the waste arm diamter to be increased one nominal trade size larger than the trap it serves therefore you could increase the waste arm to 2" which would yeild 2"/.25= 8ft.

Regardless of what type of trap is installed, if the total developed length of the waste arm exceeds 8' you would be required to install an auxillary vent for the tub.

The Uniform Plumbing code (UPC) has derated the mathematical maximums by about 50%. They list the maximum for an 1.5" line at 3ft 6in and a 2" line @ 5ft. (Check your local code authority to see which code applies in your jurisdiction)

[rdgallo]

Lazypup, do you have a diagram showing how to replace the drum trap? I think I am fed up enough to give it a try. I am not a plumber. so really don't know what I am doing.

Thanks!