Support Trunions

PIPING ENGINEERING DEPARTMENTPIPING ENGINEERING DEPARTMENT

PIPING DESIGN TIPSPIPING DESIGN TIPSby

ED MURPHY

TIP 12-MTH-01TIP 12-MTH-01

THE PIPING DESIGN TIP IS BASED ON FLUOR DANIEL AND INDUSTRY PRACTICE.

WHEN THERE IS A DISCREPANCY BETWEEN A PROJECT INSTRUCTION AND A PIPING DESIGN TIP, THE PROJECT INSTRUCTION WILL GOVERN.

IT IS YOUR RESPONSIBILITY TO IMMEDIATELY NOTIFY YOUR SUPERVISOR WHEN QUESTIONS ARISE THAT ARE NOT RESOLVED BY THE PROJECT INSTRUCTIONS.

IF YOU HAVE ANY QUESTIONS CONCERNING THIS DESIGN TIP, SEE OR CALL ED MURPHY, LOCAL 2168.

HOW TO LOCATE SUPPORT TRUNNIONSHOW TO LOCATE SUPPORT TRUNNIONS

WHAT TO CONSIDER WHEN LOCATING SUPPORT TRUNNIONSWHAT TO CONSIDER WHEN LOCATING SUPPORT TRUNNIONS

USE THIS DESIGN TIP WITH THE FOLLOWING FLUOR DANIEL DOCUMENTS:- Piping Technical Practice 000 250 2152, page 1 in Volume II of the Piping Engineering Design Guide.

Support trunnions are used to support vertical piping at the followinglocations;

- Vertical vessels

- Other equipment

- Structures

- Openings through floors and platforms

- Any place a vertical pipe needs to be supported

/tt/file_convert/55cf9455550346f57ba14cf1/document.doc

04/19/23

- 1 –noted by: eilprepared by: wilfredo cruz

*********THIS PIPING DESIGN TIP WILL ADDRESS SUPPORT TRUNNIONS AT VERTICALVESSELS ONLY - SOME OF THIS INFORMATION CAN BE USED IN THE OTHER LOCATIONS.

THE FOLLOWING INSTRUCTION, PART A AND PART B, IS EXTREMELY IMPORTANTIN DEVELOPING YOUR PIPING DESIGN ABILITY. READ IT AND APPLY IT.

PART A

The support trunnion is to be located as close to the vessel nozzle as possible - this is to be MINIMUM to reduce the effects of thermal expansion on the pipe between the centerline of the nozzle and the top of support at the trunnion.

I HAVE NOTICED ON ONE OF OUR CURRENT PROJECTS WHAT APPEARS TO BE A DEFICIENCY IN DESIGN. IN VIOLATION OF THE MINIMUM REQUIREMENT IN THE PARAGRAPH ABOVE, THERE ARE NUMEROUS TRUNNIONS AND VESSEL PIPE SUPPORTSTHAT ARE NOT PLACED MINIMUM FROM THE VESSEL NOZZLE - THIS MAY RESULTIN FORCE PROBLEMS DUE TO THERMAL EXPANSION - THE STRESS ANALYSIS HASNOT BEEN DONE YET.

WHAT CAN IMMEDIATELY BE SEEN IS THE SUPPORT TRUNNION AND VESSEL PIPESUPPORT LOCATED IMMEDIATELY BELOW PLATFORMS THAT ARE AT VESSELNOZZLES. THE PIPE DROPS DOWNWARD PENETRATING THE PLATFORM.

TO AVOID THIS HAPPENING IN THE FUTURE, I AM SUGGESTING (I DON'T HAVE PROOF) THE FOLLOWING POSSIBILITIES CAUSED THIS SITUATION - READ IT,REMEMBER IT, BUT DO NOT REPEAT IT:#1 - The pipe was routed in the configuration it should have been, but the designer did not address the need to support the pipe when he should have. In the course of the vesselorientation, the designer supported the pipe AFTER he designed the platforming. When he realized this, he added "support" below the platform so as not to have to redesignthe configuration of the platform.#2 - The minimum rule was deliberately ignored to reduce the platform size.

Whether the reason for the trunnion and it's vessel pipe support are the result of #1 or #2 or some other reason is not important at this time - what is important is that YOU DON'T DO THIS!!!

The following is an example of how to locate the trunnion MINIMUM distance as specified above AND how to locate the top of support elevation for submitting to Vessel Engineering (this is Piping's responsibility).


04/19/23


NOTE: If your task is not to locate the vessel pipe support elevation for submitting to Vessel Engineering, then the information in this Piping Design Tip can be used to identify/verify the "correctness" of the layout received by Manila from the workshare office.

GIVEN:You have an 8" line coming out of the side of a vessel and it is dropping vertically downward. At the nozzle you have fitting make-up consisting of an 8" flange and an 8" buttweld 90 degree long radius elbow.The centerline elevation of the nozzle is 190'-0".

PROCEDURE:1 - Make a FREEHAND elevation sketch of the following; The side of the vessel shell showing the nozzle, the pipe flange, the elbow, the line dropping down. It may be helpful to draw all of this double line

- whatever is easiest for you is what you'll do - but I recommend double line, my expericence has told me that to use double line works better than single line.

2 - Draw a circle on the pipe just below the elbow, representing the trunnion.

3 - Draw a horizontal line (this is the vessel pipe support furnished by the vessel vendor) out from the side of the vessel, but be sure to draw it below the circle you've drawn as the trunnion - be sure to show a small space between the bottom of the trunnion and the top of the vessel pipe support.

4 - Make a string of dimensions going from the centerline of the elbow to the end of the elbow to the top of the trunnion to the bottom of the trunnion to the top of the vessel pipe support.

5 - Place these dimensions on your sketch;Centerline of elbow to end of elbow = 1’- 0"End of elbow to top of trunnion (weld to weld) = 0’- 3"

Diameter of trunnion (from chart) = 6 5/8"Space between bottom of trunnion to the vessel pipe suport = 1/2"

6 - The total of these dimensions is 1'-10 1/8".

7 - To calculate the top of steel elevation of the vessel pipe support, subtract 1'-10 1/8" from the centerline elevation of the vessel nozzle,so;

190'-0"- 1'-10 1/8"-----------------189'-1 7/8"

We will not use fractions in determining the top of steel, so we will round the dimension to an inch increment.

So 189'-1 7/8" becomes 189'-1" NOT 189'-2". If we rounded to 189'-2" we would no longer have at least 3" minimum between welds at the end of the elbow to the top of the trunnion. /tt/file_convert/55cf9455550346f57ba14cf1/document.doc

04/19/23


It is OK to have a little more than minimum in this instance - but this is the only instance for this calculation.

The minimum requirement is satisfied with the bottom of the trunnion at 189'-1 1/2".

PART B

To have the elevation of the vessel pipe support is only part of what the Piping Designer needs to think about.

The overall dimensions of the vessel pipe support will affect platform sizing and design - especially when the vessel pipe support is within and above a platform. The Piping Designer MUST consider the 1'-6" minimum access requuired around any obstructions on a platform.

THE OVERALL DIMENSIONS OF THE VESSEL PIPE SUPPORT ARE DETERMINED ASFOLLOWS:

WIDTH- Use 2 times the "B" dimension shown for the support trunnion in Piping Technical Practice 000 250 2152. This is the extreme end of stub to the centerline of the line being supported dimension and is slightly wider than the steel structural shapes of the vessel pipe support.

DEPTH- Radial distance from the outside of the vessel shell through the pipe being supported to the outside diameter of the pipe or it's insulation - whichever is more. This will, again, be slightly more than the dimension formed by the steel structural shapes of thevessel pipe support.


04/19/23


Documents

Support Trunions