DNV DNV-RP-F104 PDF

Introduction

This Recommended Practice applies to couplings or sleeve type couplings for pipelines.

Couplings are mechanical connectors which join the pipes by direct attachment to the pipe wall. Couplings are different from flange connectors, which join pipes by aid of additional thick, machined pieces of material (the flange) welded or forged to the pipe ends prior to pipe installation.

Couplings require no welding of the pipe and the pipe ends can be:

1) Joined subsea or above sea;

2) Joined beyond diving depth where welding is not qualified;

3) Tied in to platfoims or subsea installations.

The pipe itself represents the ley inteinal component of a coupling and hence can also present limitations due to: e.g. pipe wall strength, surface irregularities and circuladstraight shape deviations. Furthermore, the coupling must be installed with caution to reduce the likelihood for e.g. seal damage.

The pressure containing capacity and the bending strength of the coupling shall at least be equal to that of the pipe, but the tension and torque strength need not necessarily meet this criteria.