Well without going on a further specific masters course in pipeline engineering you need to start working from some sort of design/ consulting company who specialise in this field or operating company.
That's quite a large field so you probably need to narrow it down a bit to a particular area/ city or field of business.
Piping and pipeline are distinct things with different design parameters and issues.
Basically get lucky one day.
I have a Mech Eng degree and didn't know a pipeline even if I fell on it before I got my first job working for a pipeline operating and engineering company and just went from there. Pure luck. And my magnetic charm of course....
Would it happen again today? I think those with the further qualifications may be in front of you, but try finding a person to advise you at one of the bigger oil companies / utility companies and ask around - do a bit of searching on line, find an industry organisation that sort of thing.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.