Back when I used to work on the aircrafts, we would have to deal with "engineers". A strange breed, who would often have no idea how to work on an airplane. But they can build them! And they are famous for putting connections of all kinds in places where you cannot swing a wrench, let alone a cat! Pesky folk, they tended to send their cubs out to "see what the technicians are doing", and after the usual pranks like being sent to fetch left handed screwdrivers and skyhooks, they tended to leave us alone. They were handy in case we needed to order stuff though.
Engineers are useful because they could come up with definitions. And definitions are useful if you are going to order "stuff". And because the guy doing the procurement has absolutely NO IDEA what we were up to (I mean how could he, we barely knew ourselves!) a proper engineering definition was essential. Failure to supply the proper material might result in cracks in the airplane...the above picture clearly shows serious cracks in the airplane. Some of them, you can see from across the hangar! So you can see how important it is to get the right product!
The definition of a length of pipe.
System Pipe Specifications With reference to B31.3,
new specifications for system pipe have been adopted by the Warranty Department on 1 Apr 04.
If the customer's pipe does not meet the following specifications, it may interfere with system operation or move the operating conditions away from those specified on the initial bid. In this case, the Warranty may be considered void and any failure will be the responsibility of the Customer.
1. All pipe shall be made of a long hole, encased by metal or plastic material concentric with the hole.
2. All pipe shall be hollow throughout the entire length.
3. Do not use holes of different length than the pipe.
4. All pipe is to be of the very best quality, perfectly tubular or pipular.
5. All acid proof pipe is to be made of acid proof metal.
6. The I.D. (inside diameter) of all pipe must not exceed the O.D. (outside diameter) or the hole may be on the outside of the pipe.
7. All pipe is to be supplied with nothing in the hole so that water, slurry or other process material can be put inside at a later date.
8. All pipe should be supplied without rust. This shall be applied at the job site by the Contractor, Fitter or Customer. Note: Some Vendors are now able to supply pre-rusted pipe. If available, this product will save a lot of time on the job site.
9. All pipe is to be cleaned free of any covering such as mud, tar, barnacles, or any form of manure before putting up, otherwise it will make lumps under the paint.
10. 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.
11. 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 if it is a long pipe.
12. All pipe over 6" (152mm) in diameter shall have the words "large pipe" painted on it, so the Fitter will not mistake it for small pipe.
13. All pipe closers are to be open on one end.
14. All pipe fittings shall be made of the same stuff as the pipe.
15. No fittings are to be put on the pipe unless specified. Otherwise straight pipe will be crooked pipe.
16. When ordering 90 degree, 45 degree or other elbows, be sure to specify right hand or left hand or the pipe will end up going the wrong way.
17. Be sure to specify horizontal, vertical, uphill or downhill sloping pipe. If downhill pipe is used for going uphill, the water will flow in the wrong direction.
18. Fittings come bolted, welded, or screwed. Always use screwed. They are the best.
19. All threaded pipe couplings should have either right hand or left hand thread. Do not mix the threads or as the coupling is being screwed on one pipe, it is unscrewed from the other.
20. Flanges must be used on all non-threaded pipe connections.
21. Flanges must have bolt holes external to and separate from the big hole in the middle. 22. Fasteners are required to hold flanges together.
23. If flanges are to be blank or blind, the big hole in the middle must be filled with metal.
24. All metal flanges must be cast or forged of the very best quality iron metal, close grained, free from blow holes, lumps, cavities, pock marks, pin pricks, and warts, otherwise we can't use them.
25. Gaskets shall be used to fill in the space between flanges
26. Gaskets are to be made of metal, rubber, plastic, paper, or some kind of goop. Do not use cow or sheep manure, it cracks when it gets dry.
27. All bolts are to be screwed.
28. All bolts must have a head on one end and a nut on the other.
Now that we have THAT straight...next week we will discuss "laying pipe".
This was a church which was placed (more or less) on the site of the Emperor Nero's grave. Apparently it was haunted, so they figured a church would fix the problem. The above sculpture by Bernini has a bas relief of Nero's tomb in behind it. 
The odor of sanctity. Pretty small church all in all. Though it is open all the time, and there are always people praying in the little chapels along the sides.
It doesn't look all that impressive from the outside. But then, that's the Roman way to do things...either its a honkin great monument, or they keep it all inside. You can tall the tourists, women with bare arms, men with puzzled looks and maps. 
What can I say? Sculpture and architecture by Bernini, art work by Carvaggio. My goodness! Names which rank up there with the best! The list of men involved in the building of this church read like a who's who of the Renaissance!
