Overview
The historical baseline reference for pipe hanger and support selection, attachment criteria, and recommended support-spacing tables for horizontal pipe runs — now fully consolidated into MSS SP-58 (2018 Edition).
Scope & Applicability
Applies To Industries
Covers — (historical baseline, now incorporated into MSS SP-58 Chapter 4 & 5) engineering criteria for selecting hanger component Types, sizing hanger rods, evaluating thermal movement, and determining maximum support spacing for horizontal pipe runs.
Does NOT cover / Superseded by — current governance lives elsewhere:
- Current Consolidated Support Standard: MSS SP-58 (2018 Edition) is the active single governing support code.
- Governing Pipe Stress & Deflection Limits: Calculated per ASME B31.1 (Power Piping) or ASME B31.3 (Process Piping) stress equations.
- Concentrated Load Support Locations: Inline heavy valves, equipment connections, and expansion joints require dedicated stress analysis, not generic spacing tables.
Key Requirements
MSS SP-69 established classic guidelines (now within MSS SP-58) for support system design:
- Support Selection Criteria: Selecting hanger hardware Types based on service temperature, operating load, and directional movement (rigid hangers vs variable springs vs rollers).
- Maximum Recommended Support Spacing: Standard spacing tables for liquid-filled vs vapor/gas-filled steel piping (NPS 1/2" to 24").
- Insulation Protection: Rules for sizing saddles and shoes to prevent insulation compression.
- Hanger Rod Sizing: Minimum rod diameters required to support liquid-filled pipe spans based on 5.0 Safety Factor.
Technical Details
MSS SP-69 was the foundational guidance document for pipe support selection and support spacing for decades before being consolidated into MSS SP-58.
1. MSS SP-69 Support Selection Matrix by Operating Service
| Operating Service & Temperature Range | Primary Movement Requirement | Recommended Support Hardware Type |
|---|---|---|
| Cold / Ambient Bare Pipe (< 150 °F / 65 °C) | No thermal movement | Type 1 Adjustable Clevis Hanger / Type 24 U-Bolt |
| Hot Insulated Pipe (150 °F – 750 °F) | Axial expansion only | Type 39 / 40 Pipe Shoe + Type 43 Pipe Roller |
| Hot Line with Thermal Expansion | Vertical movement ≤ 0.5 in | Type 51 / 52 Variable Spring Hanger |
| High Temperature Critical Line | Large vertical movement (> 0.5 in) | Type 54 / 55 Constant Support Hanger |
| Seismic / Waterhammer Area | Dynamic shock restraint | Type 58 Mechanical / Hydraulic Snubber |
2. Standard Recommended Pipe Support Spacing Table (Former SP-69 Data)
Maximum recommended spacing between rigid supports for standard weight (Sch 40) steel pipe:
| Nominal Pipe Size (NPS) | Water Service Max Span (ft / m) | Steam, Gas, or Air Max Span (ft / m) | Recommended Rod Diameter (in) |
|---|---|---|---|
| 1/2" (DN 15) | 7 ft (2.1 m) | 8 ft (2.4 m) | 3/8" |
| 3/4" (DN 20) | 7 ft (2.1 m) | 9 ft (2.7 m) | 3/8" |
| 1" (DN 25) | 9 ft (2.7 m) | 10 ft (3.0 m) | 3/8" |
| 1-1/2" (DN 40) | 10 ft (3.0 m) | 12 ft (3.7 m) | 3/8" |
| 2" (DN 50) | 10 ft (3.0 m) | 13 ft (4.0 m) | 3/8" |
| 3" (DN 80) | 12 ft (3.7 m) | 15 ft (4.6 m) | 1/2" |
| 4" (DN 100) | 14 ft (4.3 m) | 17 ft (5.2 m) | 5/8" |
| 6" (DN 150) | 17 ft (5.2 m) | 21 ft (6.4 m) | 3/4" |
| 8" (DN 200) | 19 ft (5.8 m) | 24 ft (7.3 m) | 7/8" |
| 12" (DN 300) | 23 ft (7.0 m) | 30 ft (9.1 m) | 7/8" |
| 16" (DN 400) | 27 ft (8.2 m) | 35 ft (10.7 m) | 1" |
| 24" (DN 600) | 32 ft (9.8 m) | 42 ft (12.8 m) | 1-1/4" |
3. Summary of Consolidation into MSS SP-58
All technical content of MSS SP-69 is incorporated into MSS SP-58 (2018 Edition):
- Selection Guidance → MSS SP-58 Chapter 4
- Application & Spacing Tables → MSS SP-58 Chapter 5 & Table 3
Engineering Notes
Crucial engineering guidance and common design/construction pitfalls regarding MSS SP-69 support selection and spacing:
1. The Legacy Citation Pitfall (SP-69 vs SP-58)
Although MSS SP-69 was officially withdrawn as a standalone standard and consolidated into MSS SP-58 (2018 Edition), many legacy engineering specifications, client standards, and textbooks still cite "SP-69 support spacing."
[!NOTE] When project specifications cite SP-69, treat them as direct pointers to MSS SP-58 Chapters 4 & 5. Verify component Type numbers and load ratings against the current consolidated SP-58 edition.
2. Concentrated Load Spacing Trap
Generic support spacing tables assume straight, continuous pipe runs filled with water or gas without heavy inline components.
- Mandatory Rule: Never apply generic SP-69 spacing spans across heavy inline valves, strainers, control loops, or heavy flanges. Dedicated rigid or spring supports MUST be placed immediately adjacent to concentrated load points.
3. Insulation Protection & Thermal Bridging (Type 39 / 40)
Supporting insulated hot lines directly with uninsulated pipe clamps crushes the insulation jacket and causes severe heat loss and thermal stress.
- Design Rule: Specify welded or clamped Pipe Shoes (Type 39/40) or High-Density Insulation Protection Saddles (Type 18/39) to elevate the pipe structure above the insulation envelope.
4. Vertical Riser Support Spacing
Horizontal spacing tables do NOT apply to vertical piping risers in multi-story structures or boiler towers.
- Riser Support Rule: Vertical risers require Riser Clamps (Type 8) supported at building floor slabs or structural steel levels. Riser clamps must be evaluated for thermal expansion to avoid lifting off lower supports during hot operation.
5. Deflection & Sag Limits for Liquid Piping
SP-69 spacing tables are derived to limit mid-span elastic pipe sag to 0.10 inches (2.5 mm) between supports.
- Process Risk: Excess pipe sag between supports causes liquid pocketing, air binding in water lines, and condensate pooling in steam lines (which leads to severe Water Hammer during startup).
Source, Edition & Status
- Publisher
- MSS
- Edition Year
- 2003
- Industries
- Petrochemical, Power Plant, General Industry
- Last Reviewed
- 2026-07-01
- Last Updated
- 2026-07-01
- Verified By
- Engineering content reviewer
- Content Status
- reviewed
- Official Link
- msshq.org