breaking into a pipeline.

To start, let’s correct the terminology. The term you used “to break into (a) pipeline” is called a “Tie-In” by more than 95% of the piping profession. The balance of the people use “Tie-Point” or some other term. Regardless of which of these terms you use they mean the same.

There are two basic conditions that exist when doing a “Tie-In.” The first condition is when a Tie-In must be made and the line can be shutdown and made safe for welding or other work. This is called a “Cold” tie-in. The second condition is when a Tie-In must be made and the line cannot be shutdown. This is called a “Hot-Tap” tie-in.

Some Hot-Tap tie-ins also require a procedure called “Stopple”. This is where a second Hot-Tap is made downstream of the first one. The flow is routed through the first tie-in while an articulated plug is inserted into the second Hot-Tap to blank off the flow. Various kinds of work can then be done to the remaining pipe.

The “Cold” tie-in is simple to design and install. With only a few exceptions you can handle them the same as you would for any new piping. The exceptions include:
• Make a proper survey of the condition of the existing pipe material. Is it too corroded to join the new pipe to?
• The existing line can be shut down but can the environment around the existing pipe be made safe for any required welding?

The “Hot-Tap” tie-in is more complicated. There are many, many questions and issues that need to be resolved. These include:
• Will the tie-in be a plain tie-in or a more complex “Stopple” tie-in?
• Will this be a single tie-in point or a multiple tie-in point?
• Will the tie-in be made with a “split-Tee” branch or an “O-Let” branch?
• Is there proper space available for the piping fittings and the valve?
• Is there proper space for the Hot-Tap machine and the Hot-Tap operators?
• What is the commodity? Is this commodity safe for doing a Hot-Tap?
• What is the operating pressure? Can the Hot-Tap machinery handle this pressure safely?
• What is the operating temperature? Can the Hot-Tap machinery handle this temperature safely?
• Can flow be maintained (required for cooling) during the cutting part of the Hot-Tap process?
• What is downstream (direction of flow) of the Hot-Tap that might be damaged by the cuttings from the Hot-Tap process?
• Has there been proper consultation with one or more “Hot-Tap” Specialty Contractors?

Issues for all tie-ins:
• Has Process Engineering reviewed and approved the location and type of tie-in?
• Has Plant Operations reviewed and approved the location and type of tie-in?
• Has the Installation Constructor reviewed and approved the location and type of tie-in?
• Has the tie-in location been tagged for easy and proper identification?
• Have the proper drawings been prepared and checked?
• Has the proper material been ordered?

I hope this helps.