CSA B70-19: Comprehensive Guide to Cast Iron Soil Pipe and Fittings Standard

Scope of CSA B70-19

CSA B70-19, published by the Canadian Standards Association, establishes comprehensive requirements for cast iron soil pipe and fittings intended for sanitary drainage, storm drainage, and vent pipes in building and industrial applications. The standard covers both hubless (no-hub) and hub-and-spigot configurations, including straight pipes, bends, tees, wyes, and other joint fittings. It also addresses coatings, marking, inspection, and performance testing to ensure reliability under typical service conditions.

This standard is referenced in the National Plumbing Code of Canada and many provincial building codes, making it essential for plumbing designers, contractors, and inspectors working in Canada. The 2019 edition harmonizes with major U.S. standards (e.g., ASTM A888/CISPI 301) while incorporating unique Canadian requirements for marking and product certification.

Technical Requirements and Material Specifications

Material and Manufacturing

Cast iron components must be made from gray iron conforming to the chemical and mechanical limits specified in the standard. The iron must exhibit a flake graphite structure to ensure tensile strength, compression resistance, and machinability. Pipe and fittings are produced by centrifugal casting or static casting, with strict controls on wall thickness, concentricity, and weight per unit length.

Dimensional Tolerances

CSA B70-19 prescribes detailed dimensional tables for pipe outside diameters, wall thicknesses, hub depths, and laying lengths. Both Service Weight (SW) and Extra Heavy (XH) classes are defined, with the latter requiring thicker walls for higher pressure ratings. The following table gives typical dimensions for hubless pipe:

Nominal Size (in)	Outside Diameter (in)	Wall Thickness (in) – SW	Wall Thickness (in) – XH
3	3.96	0.23	0.25
4	4.80	0.25	0.28
6	6.90	0.28	0.32
8	9.05	0.30	0.38

Tip: Always verify the class required by your project specifications. Extra Heavy pipe is often specified for commercial or industrial applications, while Service Weight may be acceptable for residential drainage.

Performance Tests

All pipe and fittings must pass a hydrostatic proof test at 345 kPa (50 psi) without leakage. Finished components are also subjected to:

Tensile test: Minimum tensile strength of 173 MPa (25,000 psi).
Impact test: Beam impact energy must exceed specified values.
Bearing (crushing) test: Pipe sections must resist ring compression loads without failure.

Implementation Highlights for Professionals

Jointing Methods

The standard covers two primary joint types. Hub-and-spigot (caulked) joints use oakum and lead or compression gaskets; they are more common in older installations and below-ground work. Hubless joints rely on stainless steel couplings with neoprene gaskets and torque‑tightened bands. CSA B70-19 references the coupling requirements of CISPI 310 or ASTM C1540 for hubless systems.

Warning: When using hubless couplings, apply a torque wrench to achieve the manufacturer’s specified tightening torque. Over‑tightening can distort the pipe or damage the coupling, while under‑tightening may cause joint leakage.

Application Considerations

Cast iron soil pipe offers excellent noise attenuation compared to plastic alternatives, making it a preferred choice for multi‑storey residential, hospitals, and libraries. The inherent fire‑resistant property of cast iron also helps maintain fire‑rated wall or floor assemblies. Horizontal runs should be supported at intervals not exceeding 1.5 m (5 ft) for hubless pipe; vertical stacks require support at each floor level. Expansion and contraction are minimal, but long vertical runs may need an expansion joint at the base.

Benefit: CSA B70-19 cast iron systems provide outstanding durability (often exceeding 50 years), high structural strength, and resistance to corrosion when properly coated and installed.

Handling and Storage

Due to the weight of cast iron, site handling must be done with mechanical lifting aids. Pipe should be stored on level, well‑drained surfaces to avoid bending or cracking. The asphaltic coating should be checked for damage before installation; any exposed bare iron must be touched up with an approved coating to prevent corrosion.

Compliance and Certification Notes

Product Certification

Manufacturers must have their products certified by an accredited agency (e.g., CSA Group, IAPMO, or UL). The standard requires that each piece of pipe and each fitting be permanently marked with:

Manufacturer’s name or trademark
Nominal size
Service class (SW or XH)
The designation “CSA B70”
The year of manufacture (if not identified by a date code)

Important: Unmarked or non‑certified products should not be accepted on a job site. They may not meet the minimum requirements of CSA B70-19 and could compromise the code compliance of the entire drainage system.

Quality Control and Inspection

The standard requires routine testing at the factory, including visual inspection, dimensional checks, and hydrostatic testing of every pipe and fitting. Audits are conducted by the certification body on a regular basis. For field installations, inspection typically involves verifying proper joint assembly, support spacing, and that no structural loads are transferred to the pipe from building components.

Relation to Other Standards

While CSA B70-19 is the primary Canadian document for cast iron soil pipe, it works in conjunction with other standards such as:

CAN/CSA B602: Mechanical couplings for drainage systems
CSA B125.3: Plumbing fittings
National Plumbing Code of Canada: Installation requirements and material approvals

Compliance with CSA B70-19 alone does not guarantee acceptance by the local authority; installers must also adhere to the applicable provincial or municipal code.

Frequently Asked Questions

Q: What is the difference between CSA B70-19 and ASTM A888?
A: CSA B70-19 is the Canadian standard for cast iron soil pipe and fittings, while ASTM A888 is the U.S. standard. They are harmonized on most technical requirements, but CSA B70 includes additional marking and certification specifics for the Canadian market and references Canadian code requirements.

Q: Does CSA B70-19 cover both hubless and hub-and-spigot configurations?
A: Yes. The standard covers both no-hub (hubless) pipe and hub-and-spigot (caulked or gasketed) joints. It provides dimension tables and performance criteria for both types.

Q: What coating is required?
A: Pipe and fittings must be coated with an asphaltic varnish or other approved corrosion‑resistant coating. The coating must be smooth, continuous, and free of blisters or bare spots. Any damage during handling should be repaired with a compatible coating prior to installation.

Q: How often are CSA B70-19 products tested?
A: Certified products are tested at least once per production run and are subject to annual factory audits by the certification body. Hydrostatic and dimensional tests are performed on each piece, and mechanical tests (tensile, impact) are conducted on a sampling basis.

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