In the North America, white PVC pressure pipe tends to be the norm rather than the grey stuff we get over here. As a result of this, nearly all white pressure pipe is manufactured to North American Standards which follow the ASTM standard. For PVC pipe this means either Schedule 40 or Schedule 80. Sch40 is the lower pressure of the two, but still exceeds the standard Class C pressure rating systems we use here in Europe.
All our white pipe and fittings have added UV stabilisers to prevent degradation in sunlight. The dimensions of our pvc pipe are as follows:
Outside Diameter mm
Pressure rating bar
Our 2" Schedule 40 pipe is supplied in 2m lengths. Our 1 1/2" Class C pipe is 3m lengths.
Effects of temperature
Like all plastic pipe, schedule 40 PVC softens as it becomes warmer. As a result of this, the pressure rating of the pipe declines by a factor or approximately 15% for every 10 degrees C over and above 20 degrees C. So at 30 degrees Centigrade, the pipe will have a pressure rating 15% less than the maximum at 20 degrees C.
A "softer" pipe will also potentially need more support. A 1 1/2" sch40 pipe will require a support every 1200mm at 20 degrees C and this will again decrease by about 15% for every ten degrees centigrade above. A 2" pipe requires support centres at approximately 1300mm.
Sch40 pipe fittings are connected in the same manner as other PVC pipe systems. The most common method is to use a solvent cement, which is brushed onto both the socket and the pipe (after first being cleaned with solvent) before being pushed together. Some fittings are threaded and here the user must be careful. Sch40 fittings that have originated in North America will have NPT threads. These types of threads are NOT compatible with any UK or European equipment. The NPT thread is not only a different "pitch" than our threads, but is tapered rather than paralell - you couldn't really get much different! Our Sch40 fittings are specially manufactured for us and have a BSPP thread on them.