1. All pipe is to be made of a long hole, surrounded by metal or plastic centered around the hole. 2. All pipe is to be hollow throughout the entire length - do not use holes of different length than the pipe. 3. The I.D. (inside diameter) of all pipe must not exceed the O.D. (outside diameter) - otherwise the hole will be on the outside. 4. All pipe is to be supplied with nothing in the hole so that water, steam or other stuff can be put inside at a later date. 5. All pipe should be supplied without rust - this can be more readily applied at the job site. 6. All pipe over 500ft (153m) in length should have the words "long pipe" clearly painted on each end, so the Contractor will know it is a long pipe. 7. Pipe over 2 miles (3.2km) in length must have the words "long pipe" painted in the middle, so the contractor will not have to walk the entire length of the pipe to determine whether or not it is a long pipe. 8. All pipe over 6" (152mm) in diameter must have the words "large pipe" painted on it, so the Contractor will not mistake it for small pipe. 9. Flanges must be used on all pipe. Flanges must have holes for bolts quite separate from the big hole in the middle. 10. When ordering 90 degrees, 45 degrees or 30 degrees elbow, be sure to specify right hand or left hand; otherwise you will end up going the wrong way. 11. Be sure to specify to your vendor whether you want level, uphill or downhill pipe. If you use downhill pipe for going uphill, the water will flow the wrong way. 12. All couplings should have either right hand or left hand thread, but do not mix the threads - otherwise, as the coupling is being screwed on one pipe, it is unscrewed from the other. N.B. Some Vendors are now able to supply pre-rusted pipe. If available in your area, this product is recommended as it will save a lot of time on the job site.