Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
---
title: Hangers and Supports for Mechanical Piping and Equipment
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# Environmental and Service Conditions {toc}
−## Material and finish selection shall account for the installed environment, because corrosion of a structural attachment is a load-path failure, not a cosmetic defect. {note}
+## Material and finish selection shall account for the installed environment, because corrosion of a structural attachment is a load-path failure, not a cosmetic defect.
### Hanger and support components shall be selected for the service temperature, humidity, and chemical exposure of their installed location.
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### At each support on insulated piping, an insulation protection shield or pipe saddle shall be provided so that the support load bears on the shield, not on crushed insulation, and the vapor barrier is maintained continuously through the support. (Insulation thermal design is specified in [[sync/mechanical-insulation]].)
−### Insulation protection shields shall be a minimum of 2 times the pipe outside diameter in length, or 12 in., whichever is greater.
−
−### Saddle and shield insert material shall suit the service temperature: high-density rigid insert (for example calcium silicate) for service above 250 °F, and high-density polyurethane or equivalent for lower-temperature service.
−
−## Omitting protection shields on insulated lines is one of the most common and most damaging specification errors. Without a shield, the hanger crushes the insulation at every support, creating a thermal bridge and a cold spot where moisture condenses; on chilled-water and refrigerant lines this drips, corrodes, and eventually rots the insulation along the entire run. The shield is not optional hardware — it is part of the support. {note}
−
```datasheet
label: Insulation protection at hanger points
…7 unchanged lines
```
+### Insulation protection shields shall be a minimum of 2 times the pipe outside diameter in length, or 12 in., whichever is greater.
+
```datasheet
label: Protection shield minimum length
…6 unchanged lines
```
+### Saddle and shield insert material shall suit the service temperature: high-density rigid insert (for example calcium silicate) for service above 250 °F, and high-density polyurethane or equivalent for lower-temperature service.
+
+## Omitting protection shields on insulated lines is one of the most common and most damaging specification errors. Without a shield, the hanger crushes the insulation at every support, creating a thermal bridge and a cold spot where moisture condenses; on chilled-water and refrigerant lines this drips, corrodes, and eventually rots the insulation along the entire run. The shield is not optional hardware — it is part of the support. {note}
+
# Hanger Rod Sizing {toc}
−## Hanger rod is sized to the rated load with a generous safety factor; the default rod diameters below follow MSS SP-58 Table 1 and ASME B31.9 and represent the 80% case for single-rod hangers on water-filled metallic pipe. {note}
+## Hanger rod is sized to the rated load with a generous safety factor; the default rod diameters below follow MSS SP-58 Table 1 and ASME B31.9 and represent the common case for single-rod hangers on water-filled metallic pipe. {note}
### Larger rods shall be used where multiple pipes share a rod (trapeze) or where the load exceeds the single-pipe assumption.
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# Structural Attachments {toc}
−## The structural attachment is where the load enters the building, and it is the connection most often left to field judgment. Every attachment method has a correct application and a way to be wrong: a beam clamp on a flange too thick to grip, a wedge anchor in a seismic zone that the AHJ will reject, a powder-actuated pin into the bottom of a hollow deck flute. The attachment shall be selected for the actual structural element and the actual load, not for installer convenience. {note}
+## The structural attachment is where the load enters the building, and it is the connection most often left to field judgment. Every attachment method has a correct application and a way to be wrong: a beam clamp on a flange too thick to grip, a wedge anchor in a seismic zone that the AHJ will reject, a powder-actuated pin into the bottom of a hollow deck flute. The attachment shall be selected for the actual structural element and the actual load, not for installer convenience.
### The structural attachment for each support shall be selected for the structural element it engages — cast-in insert, post-installed anchor, top- or bottom-flange beam clamp, channel/strut attachment, or powder-actuated fastener — and for the rated load.
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### Variable-spring hangers shall be selected so that the load change between the cold and hot positions does not exceed 25% of the operating (hot) load.
+```datasheet
+label: Variable-spring maximum load variation
+type: range
+min: 10
+max: 25
+step: 5
+unit: "%"
+default: 25
+```
+
### Where the calculated vertical displacement or the load-variation limit cannot be met by a variable-spring hanger, a constant-effort (constant-spring) support shall be provided.
−### Each spring support shall be selected from the pipe stress isometric for its cold load, hot load, and total travel, and shall be sized so the operating position falls within the working range of the spring with travel margin above and below.
−
−### Each spring support shall be furnished with a travel indicator and with travel stops that hold the spring at its cold-set position during erection and hydrostatic test.
−
−### Travel stops shall be removed after the system is filled and before the pipe is placed in thermal service, and stop removal shall be recorded for each support.
−
−### Spring supports at connections to rotating equipment shall be selected so that the residual load and load variation do not impose unacceptable nozzle loads on the equipment.
−
−## Spring supports left with their travel stops in place are a classic commissioning failure: the stop turns a spring into a rigid hanger, defeating the entire reason it was specified. Stop removal is a verifiable closeout item, which is why this Standard requires it to be recorded per support. See [[sync/commissioning]] for system turnover verification. {note}
−
```datasheet
label: Spring support type for thermally active piping
type: radio
options:
- Rigid hanger (no significant vertical travel)
− - Variable-spring hanger (load variation <= 25%)
+ - Variable-spring hanger (load variation ≤ 25%)
- Constant-effort support (large travel / sensitive load)
−default: Variable-spring hanger (load variation <= 25%)
+default: Variable-spring hanger (load variation ≤ 25%)
```
−```datasheet
−label: Variable-spring maximum load variation
−type: range
−min: 10
−max: 25
−step: 5
−unit: "%"
−default: 25
−```
+### Each spring support shall be selected from the pipe stress isometric for its cold load, hot load, and total travel, and shall be sized so the operating position falls within the working range of the spring with travel margin above and below.
+### Each spring support shall be furnished with a travel indicator and with travel stops that hold the spring at its cold-set position during erection and hydrostatic test.
+
```datasheet
label: Spring support accessories
…10 unchanged lines
```
+### Travel stops shall be removed after the system is filled and before the pipe is placed in thermal service, and stop removal shall be recorded for each support.
+
+### Spring supports at connections to rotating equipment shall be selected so that the residual load and load variation do not impose unacceptable nozzle loads on the equipment.
+
+## Spring supports left with their travel stops in place are a classic commissioning failure: the stop turns a spring into a rigid hanger, defeating the entire reason it was specified. Stop removal is a verifiable closeout item, which is why this Standard requires it to be recorded per support. See [[sync/commissioning]] for system turnover verification. {note}
+
## The cold-load and hot-load value at each spring support follows from the pipe stress analysis and shall be scheduled per support: [[drawing: spring hanger load schedule]].
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### The need for seismic bracing shall be determined from the project Seismic Design Category, the applicable ASCE 7-22 Section 13.1.4 exemptions, and the trade size of the piping, before bracing is laid out.
−### Piping requiring seismic restraint shall be braced with listed or engineered lateral and longitudinal sway braces designed for the ASCE 7-22 component force (Fp) for the system.
−
−### Lateral sway braces for piping 2-1/2 in. and larger shall be spaced at not more than 40 ft on center, and longitudinal braces at not more than 80 ft on center, unless a project-specific analysis establishes a different spacing.
−
−### Seismic braces shall attach to the structure through connections designed for the brace force, and brace anchorage to concrete shall satisfy the ACI 318-19 Chapter 17 seismic anchor provisions.
−
−### Components and distribution systems designated with a component importance factor of 1.5 (Ip = 1.5) shall be braced and anchored to remain operable or position-retained as required by ASCE 7-22 for that designation.
−
−### Seismic bracing for mechanical piping shall be designed and detailed independently from NFPA 13 fire sprinkler sway bracing; mechanical braces shall not be substituted for, nor counted as, sprinkler bracing.
−
−## The shared-member rule {note}
−
−### Where a single trapeze, strut, or structural attachment supports both mechanical piping and fire sprinkler piping, the entire shared assembly shall be designed under ASCE 7-22 with the component importance factor of the most critical system it carries (Ip = 1.5 where it carries sprinkler piping).
−
−### The design of a shared trapeze or structural attachment supporting both mechanical and fire sprinkler piping shall be coordinated between the mechanical and fire protection engineers.
−
−### NFPA 13 fire sprinkler hangers and sway braces are governed solely by NFPA 13; nothing in this Standard modifies those requirements except to require coordination on shared structures. {note}
−
```datasheet
label: Seismic Design Category (project)
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type: radio
options:
− - "Yes — <= 400 lb and CG <= 4 ft, exempt"
+ - "Yes — ≤ 400 lb and CG ≤ 4 ft, exempt"
- No — seismic bracing required
default: No — seismic bracing required
```
+### Piping requiring seismic restraint shall be braced with listed or engineered lateral and longitudinal sway braces designed for the ASCE 7-22 component force (Fp) for the system.
+
+### Lateral sway braces for piping 2-1/2 in. and larger shall be spaced at not more than 40 ft on center, and longitudinal braces at not more than 80 ft on center, unless a project-specific analysis establishes a different spacing.
+
```datasheet
label: Lateral sway brace maximum spacing
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```
+### Seismic braces shall attach to the structure through connections designed for the brace force, and brace anchorage to concrete shall satisfy the ACI 318-19 Chapter 17 seismic anchor provisions.
+
+### Components and distribution systems designated with a component importance factor of 1.5 (Ip = 1.5) shall be braced and anchored to remain operable or position-retained as required by ASCE 7-22 for that designation.
+
```datasheet
label: Component importance factor (Ip)
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```
+### Seismic bracing for mechanical piping shall be designed and detailed independently from NFPA 13 fire sprinkler sway bracing; mechanical braces shall not be substituted for, nor counted as, sprinkler bracing.
+
+## The shared-member rule {note}
+
+### Where a single trapeze, strut, or structural attachment supports both mechanical piping and fire sprinkler piping, the entire shared assembly shall be designed under ASCE 7-22 with the component importance factor of the most critical system it carries (Ip = 1.5 where it carries sprinkler piping).
+
+### The design of a shared trapeze or structural attachment supporting both mechanical and fire sprinkler piping shall be coordinated between the mechanical and fire protection engineers.
+
+### NFPA 13 fire sprinkler hangers and sway braces are governed solely by NFPA 13; nothing in this Standard modifies those requirements except to require coordination on shared structures. {note}
+
### Seismic brace locations and the bracing layout for each braced run shall be shown on the seismic bracing drawings: [[drawing: seismic bracing layout]].
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# Installation {toc}
−## Hangers and supports shall be installed so the completed system hangs level, drains as designed, and presents a verified load path at every support. The execution rules below close the gap between a correct schedule and a correct field result. {note}
+## Hangers and supports shall be installed so the completed system hangs level, drains as designed, and presents a verified load path at every support. The execution rules below close the gap between a correct schedule and a correct field result.
### Hangers and supports shall be installed in accordance with MSS SP-89 and the approved hanger and support schedule.
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# Field Quality Control {toc}
−## Installed supports shall be verified before the system is concealed or placed in service, because a missed under-rated attachment is far cheaper to find on a walkdown than after a failure. {note}
+## Installed supports shall be verified before the system is concealed or placed in service, because a missed under-rated attachment is far cheaper to find on a walkdown than after a failure.
### The Contractor shall verify, and make available for the Engineer's observation, that hanger types, rod sizes, spacing, and attachments match the approved schedule.
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- None required
```