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RACI HDPE Casing Spacers
Modular, non-metallic spacers that center and protect carrier pipe inside a casing. For carrier pipe from 1.6″ to 134″, in stock in Dallas.
Modesto, CA · Carrier pipe fitted with RACI spacers, staged for the bore · Jan 2026
Why RACI casing spacers
Since 1952
No reported failures to date.
100% HDPE
Won’t corrode and doesn’t conduct electricity.
Modular
Add or remove elements to fit any pipe size.
360° support
Stays centered even if the pipe rotates in the casing.
Tested loads
Real, published load data for every model.
No pipe damage
Soft contact, no sharp edges on the pipe.
One-person install
Lightweight, with one tightening tool.
In stock
Largest stock in North America, ready to ship.
How RACI compares
RACI HDPE spacers against the other ways to support pipe in a casing.
| RACI HDPE spacers | Other plastic spacers | Steel spacers | Wood skids | |
|---|---|---|---|---|
| Modular design | Yes | No | No | No |
| Corrosion resistance | Yes | Varies¹ | No | No² |
| Structural integrity | High | Low | High | Low |
| Availability | Stocked | Varies | Custom to order | Readily available |
| Cost | Competitive | Competitive | High | Low |
| Installation | Simple assembly | Moderate | Labor intensive | Basic, not engineered |
¹ Some plastic spacers contain metal parts that rust over time and weaken the spacer. ² Wood skids don’t corrode, but they rot and attract termites.
Casing spacer models and sizes
Pick by carrier pipe O.D., or let the sizing calculator pick for you.
| Model | Size | Carrier pipe O.D. | Runner heights |
|---|---|---|---|
| S, T | Small | 2.4–6.5 in (60–164 mm) | 0.79 in (20 mm) |
| C, D, I | Small | 1.6–7.9 in (42–200 mm) | 0.59 in (15 mm) |
| A, B | Small | 2.2–11.1 in (55–281 mm) | 0.75, 1.42, 1.97 in (19, 36, 50 mm) |
| F, G | Medium | 3.6–20.8 in (92–528 mm) | 0.98, 1.61, 2.36, 2.95 in (25, 41, 60, 75 mm) |
| M, N | Medium | 5.6–39.9 in (143–1015 mm) | 0.70, 0.98, 1.42, 1.61, 1.97, 2.95, 3.54 in (18, 25, 36, 41, 50, 75, 90 mm) |
| P, Q | Medium | 5.6–39.9 in (143–1015 mm) | 4.33, 4.73 in (110, 120 mm) |
| L | Large | 18–52 in (450–1340 mm) | 0.98, 1.61, 1.97, 2.95, 3.94, 4.92, 5.91, 6.89, 7.87 in (25–200 mm) |
| E, H | Large | 8.7–134 in (421–3400 mm) | 0.98, 1.61, 2.36, 2.95, 3.54, 4.33, 5.11 in (25–130 mm) |
How to choose a casing spacer
What we need from you
- Carrier pipe size, material, class and laying length
- Casing size, material and wall thickness
- Length of each casing section
- Whether the annular space will be grouted
The rules
- Clearance: at least 0.60 in from the runner tips to the casing, and 0.60 in from the bell to the runner tips. Where practical, no more than 2 in to the casing. The engineer may accept less on a short crossing.
- Runners: at least one per inch of pipe diameter. An 8 in. pipe needs 8 or more.
- Spacing: no more than 8 ft apart on belled pipe under 30 in., 5 ft on belled pipe 30 in. and up, and 6 ft on fused or welded pipe, center to center. One within 2 ft of each side of every bell, and double spacers at each casing end.
- Load: each spacer’s rated load must be at least the pipe’s weight per foot, full of water, times the spacing.
- No fasteners: no bands, bolts, straps or fasteners of any kind. Tape each spacer all the way around the pipe.
- End seals: 1/8 in. neoprene wrap-around seals with 304 stainless steel clamps at both casing ends.
Skip the math
The calculator does all of this for you.
It picks the model, runner height and spacing, checks your city’s spec, and draws the layout.
Where casing spacers are used
Water mains
Keeps bells and restraints off the casing wall.
Waxahachie, TX · Oct 2025
Sewer lines
Holds grade by keeping the pipe centered.
HDD
Full support even when the pipe twists on pullback.
Dual containment
Keeps the carrier centered, installs in minutes.
Oil & gas
Non-corrosive support for heavy steel carrier pipe.
Multiple carrier pipes
Several lines in one casing. We’ll review the layout.
Downloads
| Document | Format | Size |
|---|---|---|
| Casing spacer standard detail and specification | PDF, fillable detail sheet and spec section, 3 pages | 62 KB |
| RACI brochure | PDF, English | 2.6 MB |
| Folleto RACI | PDF, Español | 1.6 MB |
| Installation manual | PDF, English | 0.4 MB |
| Manual de instalación | PDF, Español | 1.0 MB |
Specification language for engineers
Download: Standard detail and specification (PDF, 3 pages). Page 1 is the standard detail, with a fillable title block; pages 2 and 3 are this section.
Part 1 – General
1.01 Summary
- This Section covers casing spacers for carrier pipe installed within casing pipe by boring and jacking, tunneling, horizontal directional drilling or open cut.
- Provide casing spacers for every carrier pipe installed within a casing, whether the casing is shown on the Drawings or installed at the Contractor’s option.
- Related Requirements: The casing, the carrier pipe, joint restraint and annulus fill are specified elsewhere in the Contract Documents.
1.02 Submittals
- Submit in accordance with the Contract Documents.
- Product Data: for each casing spacer proposed.
- Shop Drawings: for each carrier pipe and casing combination, the spacer configuration, outside diameter and runner height, the clearances to the casing and the bell, and a typical length of pipe showing the spacer spacing and the spacers beside each bell.
- Load Data: for each carrier pipe and casing combination, the weight per foot of the carrier pipe full, the maximum spacer spacing and the spacer’s published allowable load (Article 2.02).
- Substitution Requests: for any proposed substitute, submitted for the Engineer’s approval before ordering, with load calculations and other evidence that it meets every requirement of this Section.
1.03 Quality Assurance
- Source Limitations: Obtain casing spacers for every cased crossing from a single manufacturer.
1.04 Delivery, Storage and Handling
- Deliver spacers in the manufacturer’s packaging and store them off the ground, protected from damage and dirt, until installed.
Part 2 – Products
2.01 Basis of Design
- Casing spacers shall be RACI casing spacers, manufactured by RACI and supplied by Public Works Products, Dallas, Texas, or an equal approved by the Engineer that meets every requirement of this Section.
- The spacer manufacturer shall maintain a quality management system certified to ISO 9001.
2.02 Casing Spacers
- Casing spacers shall be all high-density polyethylene (HDPE), modular, projection-type spacers with integral nonmetallic locks, assembled around the pipe from interlocking segments whose number is set by the carrier pipe diameter. No bands, bolts, straps or mechanical fasteners of any material are permitted, so that the carrier pipe stays electrically isolated from the casing.
- The number of projections (runners) per spacer shall be equal to or greater than the carrier pipe’s nominal diameter in inches (for example, an 8 in. pipe requires a minimum of 8 runners).
- Runner height: selected so that:
- The spacer outside diameter is smaller than the casing inside diameter, with enough clearance to pass the internal weld beads at the casing joints and any misalignment of the casing without binding.
- Where practicable, the clearance between the spacer and the casing is not more than 2 in.
- On belled pipe, the spacer outside diameter is larger than the bell outside diameter, so the spacer rides on the casing and the bell does not touch it.
- The clearances for each crossing are as shown on the Drawings.
- Each spacer shall carry a published allowable load not less than the design load per spacer. The design load per spacer is the weight per foot of the carrier pipe full of water, or of its contents where heavier, multiplied by the spacer spacing shown on the Drawings for that crossing.
Part 3 – Execution
3.01 Examination
- Verify the actual casing inside diameter and carrier pipe outside diameter before ordering spacers, and confirm that the selected runner height provides the clearances shown on the Drawings.
3.02 Spacer Placement
- Install casing spacers in accordance with the manufacturer’s written instructions. Where those instructions conflict with this Section or the Drawings, the more stringent requirement governs.
- Place a spacer on each side of every bell and space the others between them, no farther apart than the spacing shown on the Drawings. Where the Drawings state no spacing or bell distance for a crossing, the following maximums apply, measured center to center:
- Bell-and-spigot pipe smaller than 30 in. nominal diameter: 8 ft maximum, with a spacer within 2 ft of each side of every bell or coupling.
- Bell-and-spigot pipe 30 in. nominal diameter and larger: 5 ft maximum, with a spacer within 2 ft of each side of every bell or coupling.
- Continuous pipe with fused or welded joints (HDPE, steel, copper): 6 ft maximum.
- For small-diameter carrier pipe the Drawings show a closer spacing where needed to limit deflection between spacers; that spacing governs.
- Provide at least the number of spacers shown on the Drawings, and more where the manufacturer’s written instructions require them.
- Provide double spacers at each casing end where the Drawings show them.
- Position and restraint:
- Assemble the spacers to support the carrier pipe and hold it in position while it is pushed through the casing.
- Restraint against flotation and movement in service is specified elsewhere in the Contract Documents. The spacers position the carrier pipe; they restrain it only where the Drawings so state.
- Center the carrier pipe within the casing where the Drawings call for centering. Otherwise the runner height shown on the Drawings sets the position of the carrier pipe in the casing.
- Do not place a spacer on a bell, coupling or joint. Locate spacers on the barrel of the pipe, clear of joint hardware.
- Secure each spacer with the double-sided butyl tape included with the spacers, around the full circumference of the carrier pipe, to prevent it from sliding along the pipe.
- Provide 1/8 in. neoprene wrap-around end seals with 304 stainless steel clamps at each casing end.
3.03 Field Quality Control
- Before the casing ends are sealed or the annular space is filled, confirm at each end of the casing that the carrier pipe bears on its spacers with clearance at the top of the spacer and that neither the pipe nor its bells touch the casing.
End of Section
Common questions
About casing spacers
Why use casing spacers instead of wood skids?
Casing spacers ensure proper grade and alignment. Wood skids can rot, shift, or attract termites — causing unbalanced support that risks pipe damage or misalignment. Spacers give consistent, long-term protection.
What is the difference between centering and restraining?
Centering means keeping the carrier pipe evenly spaced within the casing. Restraint refers to limiting vertical movement. Most centered pipes are restrained, but not all restrained pipes are centered. Leave at least 0.60″ between the spacer and the casing so it doesn’t bind going in.
Do all installations require the carrier pipe to be centered and restrained?
Centering or restraining is critical for sewer lines and recommended for water lines. Sewer pipes must stay fixed to prevent floating, which can cause sediment buildup or backflow. Water pipes should also be restrained to avoid movement from pressure changes that may lead to wear over time.
Can RACI spacers be used in both dry bores and grouted installations?
Yes. RACI spacers are designed for both dry bores and grouted installations. Their runners allow grout to flow smoothly without creating voids or obstructions.
What kind of loads can your spacers handle?
Load capacity depends on the model, but our strongest spacers support up to 11,000 lbs. Our sizing tool (www.pwpracisizing.com) and quote process both account for pipe weight when full of water, and recommend tighter spacing if needed.
Are RACI casing spacers compliant with ASTM and ISO standards?
RACI casing spacers are manufactured in an ISO 9001-certified facility. They are tested in accordance with relevant ASTM standards, including ASTM D638 for tensile properties and ASTM D2240 for hardness. A full list of tested properties is available in our brochure. An ISO 9001 certificate is available upon request.
How far apart should spacers be installed?
Measured center to center: no more than 8 feet apart on belled pipe under 30 inches, 5 feet on belled pipe 30 inches and up, and 6 feet on continuous pipe with fused or welded joints (HDPE, steel). Put a spacer within 2 feet of each side of every bell or coupling, and double spacers at each end of the casing. Small pipe may need closer spacing so it doesn’t sag between spacers, and the spacing on the project drawings always governs.
Can spacers be installed on ductile iron, HDPE, or PVC pipes?
Yes. Our spacers work with all pipe types, including ductile iron, HDPE, and PVC. Because they’re made entirely of HDPE, they also eliminate the risk of electrical conductivity between the pipe and casing.
Are RACI spacers approved by municipalities or government agencies?
Yes. RACI spacers are approved by many municipalities and agencies across the U.S. and internationally. If you’re unsure about your project’s approval status, reach out to us through our contact page and we’ll help confirm.
How long do the spacers last?
When properly installed, RACI spacers are designed to outlast the life of the pipe. They require no maintenance and are unaffected by corrosion or soil conditions.
Ordering and installation
How quickly can orders ship out?
For most orders, Public Works can offer same-day shipping if received before 2 PM. Larger or complex orders are typically prepared for next-day shipment.
Can you provide submittals or documentation for project approval?
Yes. We can provide submittals, letters of compliance, and formal request letters for approval. If needed, we also offer application-specific submittals tailored to the project or municipality to help get our products approved.
How do I know what spacer model and height to choose?
Spacer selection depends on project specs, but as a rule of thumb, pick the runner height so there’s at least 0.60″ from the bell or restraint to the runner tips, and at least 0.60″ from the runner tips to the casing ID. Where practical, keep the gap to the casing under 2″. Use at least one runner per inch of pipe diameter (an 8″ pipe needs 8 or more). Length and casing condition may also affect the final selection. You can use our online sizing calculator to enter your details and view available spacer options.
What information do I need to request a quote?
At a minimum, please provide:
- Carrier pipe type and size (include restrainer OD if used)
- Casing pipe type and size
- Length of bore
For best results, also include:
- Project details (location, specs)
- Whether pipe needs to be centered, restrained, or just clear the bell
Can you support multiple carrier pipes in one casing?
Yes. RACI spacers can often support multiple carrier pipes in a single casing. Our engineering team will review the layout and recommend a solution based on your project needs.
Can RACI spacers be customized for special applications?
Yes. Custom spacer configurations can be provided on a project-by-project basis. Contact us with your application details to explore options.
What runner heights are available? Can you do low-clearance configurations?
Runner heights range from 0.59″ to 7.87″. RACI’s modular design allows for low-clearance solutions and tight-tolerance applications.
How are the spacers secured to the pipe? What kind of tape is used?
Each spacer comes with double-sided butyl tape, enough to wrap fully around the carrier pipe. Once installed, the spacers stay securely in place and will not slide during insertion. Tape adhesion test results are available upon request. The spacers lock together with built-in plastic locks, so no bands, bolts or other fasteners are used.
Does Public Works Products offer emergency assistance?
Yes. For after-hours, weekend, or emergency service, contact us and someone from our team will respond immediately.
Ready to order?
Size it online or call us. Most orders ship the same day.