Check the standards you are supposed to adhere to in your project for the pipes.
Remember that imported equipment might come with different flange drilling than what your pipe flanges have.
There are a number of different flange and pipe standards, make sure you allow for this in the designs. Most standards (such as ANSI, BS, AS, PN etc) are not interchangeable.
The details you give your design team need to match the right standard. You could be ordering a pump with a AS2129 Table D flange, but your designers might assume the project is using a British standard, or ISO standard because other equipment is listed as matching those specs.
It is easy to overlook this. In fact if you aren’t careful you will only realise when your installation team calls to tell you that the pumps and pipes don’t match. Then you waste time and money working out a solution.
While on this topic, make sure you understand the differences between the standards dimensions and also the faces of the flanges they describe (e.g. flat faces, raised face, etc).
Most suppliers of pipes will have a page showing sizes, flanges, drilling, and comparisons in their catalogue.
Early planning and checking can save a lot of time later in the project.