Can Anyone Explain me About Hot Tapping and Cold Tapping?
Specially Mr. Jop
A "Tie-In" is the connecting of new piping to existing piping.
There are two basic conditions that exist when doing a â€œTie-In.â€
- 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 â€œColdâ€ tie-in.
- The second condition is when a Tie-In must be made and the line cannot be shutdown. This is called a â€œHot-Tapâ€ tie-in.
Some Hot-Tap tie-ins also require a procedure called â€œStoppleâ€. 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 â€œColdâ€ 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:
â€¢ Make a proper survey of the condition of the existing pipe material. Is it too corroded to join the new pipe to?
â€¢ The existing line can be shut down but can the environment around the existing pipe be made safe for any required welding?
The â€œHot-Tapâ€ tie-in is more complicated. There are many, many questions and issues that need to be resolved. These include:
â€¢ Will the tie-in be a plain tie-in or a more complex â€œStoppleâ€ tie-in?
â€¢ Will this be a single tie-in point or a multiple tie-in point?
â€¢ Will the tie-in be made with a â€œsplit-Teeâ€ branch or an â€œO-Letâ€ branch?
â€¢ Is there proper space available for the piping fittings and the valve?
â€¢ Is there proper space for the Hot-Tap machine and the Hot-Tap operators?
â€¢ What is the commodity? Is this commodity safe for doing a Hot-Tap?
â€¢ What is the operating pressure? Can the Hot-Tap machinery handle this pressure safely?
â€¢ What is the operating temperature? Can the Hot-Tap machinery handle this temperature safely?
â€¢ Can flow be maintained (required for cooling) during the cutting part of the Hot-Tap process?
â€¢ What is downstream (direction of flow) of the Hot-Tap that might be damaged by the cuttings from the Hot-Tap process?
â€¢ Has there been proper consultation with one or more â€œHot-Tapâ€ Specialty Contractors?
Issues for all tie-ins:
â€¢ Has Process Engineering reviewed and approved the location and type of tie-in?
â€¢ Has Plant Operations reviewed and approved the location and type of tie-in?
â€¢ Has the Installation Constructor reviewed and approved the location and type of tie-in?
â€¢ Has the tie-in location been tagged for easy and proper identification?
â€¢ Have the proper drawings been prepared and checked?
â€¢ Has the proper material been ordered?
Cold Tie-In Procedure
I have a Piping Fabrication and Installation Procedure. Is this procedure the same as tie-in procedure? If they are different, does anybody have a cold tie-in procedure?
There are a number of questions that come up as a result of your question.
â€¢ What is covered in the Piping Fabrication and Installation Procedure?
â€¢ Are you sure you will be doing a â€œcoldâ€ tie-in?
â€¢ Who are you in the overall picture of this Tie-in? Are you the Client? The primary engineering company planning the Tie-in? Or are you the Mechanical Contractor who will be overseeing the actual Tie-in? Or are you someone else in the grand scheme of things?
â€¢ What is the line size and wall schedule of the tie-In?
â€¢ What is the commodity normally in the line?
â€¢ How far to the closest valves up stream and downstream of the Tie-in Point?
â€¢ Can the upstream and downstream piping be drained and steamed out?
1. Identify each Tie-In(s) schematic location on P&ID - Process Engineer
2. Review with Piping - Process & Piping Design
3. Create a Tie-In Index (or List) with key information about each Tie-In - Piping Design & Process Engineer
4. Review with Client - Process Engineer
5. Go to the Field to locate physical point of Tie-In - Piping Design/Process
6. Meet with plant personnel and review Tie-In requirements - Piping Design, Process, Plant Operations, Safety
7. Discuss different types and configurations of Tie-Ins - Piping Design, Process and Plant personnel
8. Establish physical Tie-In location point and type - Piping Design & Plant Personnel
9. Define if the line can be shut â€“down, when, how long, draining, depressurize, steam-out and other safety issues - All personnel
10. Visually inspect the existing pipe. Are more extensive tests needed to determine condition and suitability for the Tie-In? - Piping Design and Plant personnel
11. Mark or tag the selected Tie-In point - Piping Design & Plant Personnel
12. Photograph the Tie-In point - Piping Design
13. Draw sketch and take all required measurements - Piping Design
14. Determine locations of all existing block valves, vents and drains - Piping Design
15. Determine the location of all existing anchors and guides - Piping Design
16. Based on selected Tie-In location and type determine if additional vents or drains will now be required - Piping Design, Plant Operations
17. Include new vents or drains (if any) on sketch - Piping Design
18. Insure that this process is followed for all Tie-Ins - All participants
19. Get plant personnel to sign off on all data collected in the field - Piping Design & Process Engineering
20. In the office modify the P&ID as required - Process Engineer
21. Convert all field sketches into appropriate production drawings (Isometrics) - Piping Design
22. Prepare a Plot Plan style â€œTie-In Location Key Planâ€
23. Update the Tie-In List as required - Piping Design
24. Review all Tie-Ins with Pipe Stress for effect on existing system piping and new system piping - Piping Design
25. Finalize (check, correct and approve) all Tie-In isometric drawings - Piping Design
A "Tie-In" List will normally have a Title Block area and a Tie-In List â€œData" area.
Note: [piping] indicates responsibility
The Title Block area should have the following]
- Tie-In No. [piping]
- P&ID No. [piping]
- Piping Plan No. (new) [piping]
- Tie-In Iso. No. (if different than Line Number)[piping]
- Line No. [piping]
- Conn. Type [piping]
- Commodity [piping or process]
- Oper. Press. (this should be the same as the existing line so you do not need it twice)[piping or process]
- Oper. Temp. (this should be the same as the existing line so you do not need it twice) [piping or process]
- Test Media [piping]
- Test Press. [piping]
- NDE Req'd. [piping]
For existing line being tied into]
- Exist. Line No. [piping]
- Exist P&ID [piping]
- North Coord. [piping]
- East (or West) Coord. [piping]
- Center line Elev. [piping]
- Welding Comp/tested [construction]
- Schedule Shut-down [Client]
- Completion Client Sign-Off [Client]
Do it once and Do it Right
Boy I can't beat JOP's explanation!
..."HOT" means welding is involved, and "COLD" means some type of mechanical branch connection that is bolted in place. Hot taps you usually see O-lets, saddles, split-tees, & plain stub-in welded on a main line and a full port valve is added to this new branch connection, then a drilling/coring machine is hooked up to the valve ...then thru the valve a hole/coupon is cut thru the wall of the main line. "IF" a coupon is cut, it is then drug back thru the valve to remove it, the valve is closed and you now have an active branch connect for the commodity in the main line. NOTE - IF you used a drill bit to make the hole (normally in smaller sizes 1 1/2" & down) you will end up with shavings from the drilling operation in the main line, so "IF" that is an issue a filter/strainer needs to be present down stream of this location.
I see a fair amount of "cold" connections being use these days, usually on low temp critical commodities ...fuel gas, vapor recovery headers, vacuum lines, exotic alloy pipe, etc. These are "saddles" that are held in place with U-bolts, the branch connection on these saddles have a large/thick O-ring type gasket to seal this attachment, these tend to be on the smaller size (biggest I've seen is 4"). They are quickly done, can be done by the tech.s (no welding needed for initial connection), and are cheaper (over all connection cost).
Thank you very much Mr. Jop and Mr. 11echo
i understood very well
thanx once again
FYI â€¦Iâ€™ve received an Emailed from a fellow piper with long experience that disagrees with my post above on this topic. His contention is ALL branch connections into â€œliveâ€ lines are Hot Taps, and Cold Connections are branch additions to the main header when it is shut down and cleaned out for normal construction.
20 years ago I would have agreed with this individualâ€™s concept! BUT whether we like it or not this is a changing industry (especially in the last 10 to 15 years), and I believe this is one of those changes. Actually I like this change, young engineers and designers can equate alittle better with the definition I posted above â€¦Hot equals â€œweldedâ€ & Cold equals â€œnot weldedâ€, and for clarification this is in regards to â€œtappingâ€ into a â€œliveâ€ line.
Iâ€™m not trying to shoot anybodyâ€™s definition down here, Iâ€™m only reporting my experience and how these types of connections are called out with the major oil company I presently work with. My goal here is to put out more information and to Iâ€™ll leave it up to the readers here as to how theyâ€™ll handle it in their part of the world.
FYI â€¦I see a fair amount of "cold" connections being use these days, usually on low temp critical commodities ...fuel gas, vapor recovery headers, vacuum lines, exotic alloy pipe, etc. These are "saddles" that are held in place with U-bolts, the branch connection on these saddles have a large/thick O-ring type gasket to seal this attachment, these tend to be on the smaller size (biggest I've seen is 4").
I've never seen or heard of this, and I'm having a hard time visualizing it. Half saddle or full saddle? Are the O-rings on the saddle or the branch? If on the saddle, are there two halves to the saddle and how would the seam be sealed? If on the branch, how do you seal the saddle on the header (surely U-bolts alone won't suffice), and what type of connection forms the branch? There must be cutting involved into the header, much like the removal of a hot tap coupon?
Getting more back on topic, it is very gracious of you to share your friends comments. Not to be contrary, because I too agree that the world is full of differring interpretations of terminology, but I have to agree with your friend. Hot tapping by my definition is welding onto and cutting into a live line while it remains in service. Cold tapping is joining into a line taken out of service, either by spool replacement between two flanges, with the added branch as you describe, or cutting a tee or O'let into the line by welding. The former requiring of a cold work permit (no welding) and the latter requiring of a hot work permit (welding required).
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