Try this, it might clear things up for you ... or confuse you !!
The integrity of a piping system depends on the considerations and principles used in design, construction and maintenance of the system.
Piping systems are made of many components as pipes, flanges, supports, gaskets, bolts, valves, strainers, flexibles and expansion joints.
The components can be made in a variety of materials, in different types and sizes and may be manufactured to common national standards or according to a manufacturers proprietary item.
Some companies even publish their own internal piping standards based upon national and industry sector standards.
Piping codes and standards from standardization organizations as ANSI, ASME, ISO, DIN, EN and others, are the most common used in pipes and piping systems specifications.
The difference between piping codes and piping standards can be defined as:
Piping Codes
Piping codes defines the requirements of design, fabrication, use of materials, tests and inspection of pipes and piping systems.
A code has a limited jurisdiction defined by the code.
Piping Standards
Piping standards define application design and construction rules and requirements for piping components as flanges, elbows, tees, valves etc.
A standard has a limited scope defined by the standard.
There is another way to look at it. Take ASME B31.3 for example. The cover page defines it as an "American National Standard". However, in all 50 states and 10 provinces of Canada, the local legislatures have adopted these standards as the "law", therefore "codifying" them. Thus, the Standard becomes a Code. For other places in the world where this standard is not required to be followed by law, then it remains simply a standard.
I'm afraid I don't see the distinction - to me a code is a standard. Some standards can be more limited in scope than others, but that doesn't mean codes can't be called standards.
Taking TGS4's example of ASME B31.3, the cover page does define it as an "American National Standard", but further up the same page it also indicates that it is part of the "ASME Code for Pressure Piping, B31". That might suggest that all the B31 parts, each an American National Standard, might make up the "Code", but within the text reference is made to "This Process Piping Code..." indicating that B31.3 is also a code. These words are there whether the document is taken into law or not.
Most standards are voluntary and are only given life if referred to in a specification in a contract. Codes on the other hand exist in law to protect the public and as such are mandatory.
Even where they are mandatory some provisions require the agreement or specification by the end user. Thus risks are apportioned to those best able to handle the risks.
