What is your main career?. To my knowledge, Pipeline Engineering is the same as "Petroleum engineer" (If I am not mistaken), therefore its NOC is 2145. A quick search over the internet seems to back up my claim, but you cannot claim this NOC if your career does not match it. A Civil/Mechanical/Chemical Engineer cannot use this NOC unless you have undergraduate or post-graduate studies on it.
- Job tittles aren´t important.
- Your career´s name tells you the appropriate NOC most of the time.
- Work experience letter duties must match some of the NOC listed main duties.
Now check if the duties listed under your work experience letter do match the responsibilities listed under your real NOC, if you have Civil Engineer studies alone, your NOC is 2131 and your work experience duties should match some of the responsibilities listed for 2131. If you have petroleum/pipeline engineering studies your NOC is 2145 and your work experience duties should match some of the responsibilities for 2145.
My humble advice?, just get a job offer and skip the whole process ASAP, if you are a petroleum engineer, this career is on demand.