Is anyone having any literature / basis / company guideline regarding:-

1. Minimum natural frequency required for two phase flow carrying piping . ( 2 Hz or 4 Hz?)
2. Minimum natural frequency required for transfer lines in refineries with two phase flows . ( 4 Hz or more ?)
3. Slug / plug flow lines ( 5 Hz or more?)

Regards,

bag_piper

Norsok gives GUIDANCE about minimum natural frequencies. They are relevant to smaller bore systems, i.e. not big bore FCC unit pipework etc.

There are no mandatory limits.

You need to use some good engineering judgement.

DNV‐RP‐D101 Clause 2.2.7.1 specifies 4-5 Hz.

Danorc,

Your reference to DNV‐RP‐D101 is correct, but it is ONLY recommended practice. It is not a requirement, nor is it pipe size specific.

Reading the Foreward to DNV‐RP‐D101 it is clear that the document is aimed at offshore appllications. See my comments above.

Everything I've seen on this topic is "Recommended Practice", or a "Guideline". These may be pulled into a project as "requirements", but I've never seen a published requirement for a minumum natural frequency.