ERGNA Engineering
Stress analysis for PNG risers in high-rise buildings
We check the gas riser for thermal movement, wind sway, seismic effect and settlement, so the pipe stays safe for the life of the building.
Approved vendor
Registered vendor of Mahanagar Gas Limited
ERGNA Engineering is a registered vendor of Mahanagar Gas Limited (MGL) for the design, engineering and stress analysis of pipe natural gas networks in high-rise buildings. MGL vendor code: 208165.
See completed high-rise projects →- 22
- Projects completed
- 35
- Towers
- 8,174
- Flats covered
- 292 m
- Tallest tower
Deliverables
What you receive
The analysis is done for the builder, the MEP consultant or the installer, and covers the whole riser from the base to the top floor.
- A stress analysis report with every load case and result
- A support, clamp and guide layout for the installer
- Recommendations for expansion loops, bellows or guided supports
- A cross-check of the floor-by-floor sway table against the structural data
- Revisions when the building design data changes
Background
Why it is needed
A gas riser in a tall building is a long steel pipe fixed to a structure that moves with temperature, wind, earthquake and settlement. Without a calculation, that movement can overstress welds, joints and supports. Read our guide to PNG riser stress analysis. Related guides: sway and seismic loads, expansion loops and bellows, what the report should contain and why every tower needs its own analysis.
- PNGRB T4S regulations: expansion and flexibility evaluated at 65 °C, with design calculations for combined loads
- PNGRB guidelines for multi-occupancy buildings (2020): stress analysis for buildings over 40 metres, with sway, seismic and thermal cycle checks
How the analysis runs
Five steps, from the first data request to the handover.
Collect the data
The riser layout and isometrics, the building height and floor levels, the shaft details, and the structural designer's sway and seismic data.
Build the model
The riser, supports and guides are modelled with the design basis of 20 °C at installation and 65 °C in service.
Run the load cases
Pressure, self-weight, settlement, thermal expansion, sway in each direction and seismic effect are checked one by one and in combination.
Review and refine
Stresses, support loads and movements are compared with the limits. Expansion loops, bellows or guided supports are added where the pipe needs them.
Report and hand over
The report, the support and flexibility layout and the sway-table cross-check go to the builder and the installer, and we support the as-built drawings.
Common questions
Is a stress analysis required for every high-rise building?
The PNGRB guidelines for gas supplies to multi-occupancy residential buildings (2020) require a stress analysis for buildings taller than 40 metres. The gas distribution company may have requirements of its own as well, so confirm them at the start of the project.
What information do you need to start?
The riser route and floor levels, the building height, the shaft sizes, the pipe sizes and pressure, and the sway and seismic data from the structural designer. If something is missing, we tell you what to ask for.
What does the report contain?
The design basis, the load cases, the results for pipe stress and support loads, the movements at each level, and the supports, guides and expansion devices the pipe needs.
Why do taller towers need more care?
Longer risers collect more thermal growth, sway at the top of a tower is larger, and support loads add up down the riser. A layout that works for a 40 m building can be overstressed at 120 m or more.
When should the analysis be done?
At the design stage, before the riser and its supports are fabricated and fixed to the building. Changes after installation take time and cost more.
Are you registered with Mahanagar Gas Limited?
Yes. ERGNA Engineering is a registered vendor of Mahanagar Gas Limited for design, engineering and stress analysis of pipe natural gas networks in high-rise buildings. The MGL vendor code is 208165.