In the construction industry there is a very famous photograph of a bridge construction. The construction programme called for the bridge to be built from both sides at the same time and meet in the middle. Progress on the construction of both sides continued well until the contractor was getting ready to install the last section to make up the gap. It was only then that they realised that there had been an error in the surveying on each side and the two sides were actually at different heights, creating a step.
This is something where those not involved can all laugh, but it can be a relatively simple mistake to make. When designing and installing a new pipeline the complete installation is uniformly specified and installed, ensuring that all of the pipe lines, pipe fittings and flanges are compatible.
When carrying out a modification to an existing pipeline however, things can become a little trickier. First of all the age of the pipe has to be determined as this can help to establish if it was built to imperial or metric standards.
Secondly the size of the pipe has to be determined. Pipes can be specified in size by their outside diameter (O.D.) or by their nominal bore (N.B.) Depending on the wall thickness these will give different pipe sizes for a given measurement. So measuring the existing pipe but then selecting from the wrong pipe tables could mean that the new section of pipe may be the same size on the outside but completely different on the inside which will make it difficult to fit and could cause a restriction in the flow.
We at Chemi Petro manufacture pipes to a range of sizes, standards and wall thicknesses and to O.D and N.B. dimensions so you will be sure to get the right product. Just make sure you measure it correctly in the first place.