Friday, December 03, 2004

Schedule 40

I loathe days like today. I spent it driving a hundred miles to make 3 stops. Worse than this, I was under a tight deadline to get to my last stop before they closed at 4:30pm. This was necessitated for wont of a vent pipe. The two feet of 4" vent pipe that will stick up above the roof. Often this is left as the 4" of black ABS, painted or covered by some metal roof jack. In my case this was to be, like everything else, stainless steel.

The Zs had volunteered to come up with a piece through their contacts, but suddenly on Wednesday they realized that they were about to cover that area of the roof, and they had no solution. I was in Astoria all day Thursday, and they agreed to solve the problem that day. When I returned home, I swung into the new driveway in the darkness and directed my headlights onto the roof. Little or no progress and no vent tube.

Thus I found myself this morning having to come up with a piece of pipe. Being Friday it was important to get something that day in case our spate of rain-free weather continued. The gods were dangling the good weather in front of us, and we were blowing it. In these past 3 days the roof could have been virtually finished.

I turned to Northwest Metal Products again. They were as responsive as usual, but if we were going to do something with what was on hand, I would have use "schedule 40" stainless steel pipe. I have seen and used the term often, but like so many things in life that we are familiar with, in truth we have no clue what they mean. In this case schedule 40 is the common minimum standard for DWV pipe, for example.

What I had originally wanted was a very thin piece of tubing as a mere cosmetic cover to the pipe or even to couple to the system via what is called a "hubless" coupler. In either case I had in mind something maybe 1/32 of an inch thick. I learned that pipe is really only specified by its outer dimension. I then made the wrongheaded logical jump to conclude in my own mind that surely schedule 40 4" stainless steel pipe would naturally be much thinner than 4" plastic pipe. This notion is further obscured to the novice because schedule 40 pipe is routinely referred to as "thin wall" pipe in the industry even though ABS DWV pipe is 1/8" thick.

In any case, although a c-note to acquire, I ordered it under a bit of duress, and then fled my house to make my own schedule

Boy was I surprised when North West presented me with a nicely polished hunk of tubing weighing in at a good 20 pounds. Remember, it is only 2 feet long. Turns out that schedule 40 is exactly that, a schedule. It's not a formula or a chart, but a schedule where one must look up the material, and nominal diameter and with this determine what schedule pipe to choose to meet one's other requirements. Turns out I really wanted was schedule 10S or even 5S stainless tubing.

One end of my vent pipe is precisely cut at 30 degrees to match the slope of the roof, and northwest had polished it up quite nicely. It is really too beautiful to mount on the roof, and I'm considering keeping it in the living room as a monument to how even the best intentioned modest projects can turn to folly and excess.

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