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CSA HPIT 2-2017: Comprehensive Technical Overview of High-Pressure Intensifier Tank Standards
Design, Material Selection, and Compliance for High-Pressure Industrial Tanks
Scope and Application
CSA HPIT 2-2017, part of the High-Pressure Intensifier Tanks (HPIT) series, specifies the minimum requirements for the design, material selection, fabrication, inspection, testing, and certification of stationary high-pressure intensifier tanks used in industrial fluid power systems, oil and gas processing, and pressure boosting applications. The standard applies to tanks with a maximum allowable working pressure (MAWP) greater than 10 MPa (1 450 psi) and less than or equal to 40 MPa (5 800 psi), designed for non-lethal service where the contained fluid is non-corrosive or mildly corrosive. It covers both seamless and welded construction, with a maximum design temperature of 200°C (392°F).
Tip: CSA HPIT 2-2017 is intended to harmonize with ASME Boiler and Pressure Vessel Code Section VIII, Division 1, while adding specific Canadian requirements for cold-weather operation and toughness qualification.
Technical Requirements and Material Specifications
Design Criteria
The standard adopts a design-by-rule approach. Minimum wall thickness for cylindrical shells is calculated using the formula:
t = (P * R) / (S * E - 0.6 * P)
where P is the MAWP, R is the inside radius, S is the allowable stress, and E is the joint efficiency. All pressure-containing parts must meet the toughness requirements of CSA W59 or an equivalent fracture mechanics assessment at the minimum design metal temperature (MDMT) of -30°C (-22°F).
Material Specifications
Table 1 lists the preferred material grades and their mechanical properties as permitted by CSA HPIT 2-2017:
| Material Grade | Specification | Min. Yield Strength (MPa) | Ultimate Tensile Strength (MPa) | Allowable Stress at 200°C (MPa) |
|---|---|---|---|---|
| SA-516 Gr. 70 | ASTM A516/CSA G40.21 | 260 | 485–620 | 138 |
| SA-537 Cl. 1 | ASTM A537 | 345 | 550–690 | 172 |
| 304L Stainless Steel | ASTM A240 | 170 | 485 | 115 |
| SA-350 LF2 | ASTM A350 | 250 | 485–655 | 138 |
Warning: Carbon steel materials used in tanks with design temperatures below -20°C must undergo Charpy V-notch impact testing at the MDMT with average energy of at least 27 J (20 ft·lbf).
Fabrication and Welding
Welding procedures must be qualified in accordance with CSA W47.1 (steel) or CSA W47.2 (aluminum). All butt-welded joints require 100% radiography using a technique that can detect a 2% sensitivity. Nozzle reinforcement areas follow the area-replacement method of ASME VIII-1. Tanks made from quenched-and-tempered steel require post-weld heat treatment (PWHT) when the thickness exceeds 40 mm.
Implementation Highlights
To assist manufacturers and certifiers, the standard introduces three design categories (Categories I, II, III) based on the product of MAWP and inside diameter (MPa·m). Category III vessels (PD > 5.6 MPa·m) require a complete fracture mechanics analysis and a full set of nondestructive examinations (NDE).
- Nondestructive Examination: Mandatory tests include hydrostatic test (1.25 × MAWP), magnetic particle inspection (MPI) of all welds for ferritic steels, and ultrasonic examination (UT) of all plate material over 50 mm thickness.
- Marking and Documentation: Each tank must be permanently marked with the standard number, MAWP, MDMT, manufacturer’s name, and serial number. A data report conforming to CSA HPIT 2-2017 Annex A must accompany each tank.
- Cold-Weather Provisions: For installations where ambient temperature can drop below -40°C, the standard mandates a supplementary toughness evaluation using the reference temperature method described in CSA Z662.
Note: Many Canadian jurisdictions have adopted CSA HPIT 2-2017 as a regulatory standard. Early engagement with a recognized certification body (e.g., CRN registration) is highly recommended.
Compliance and Certification
Compliance with CSA HPIT 2-2017 is typically demonstrated through third-party inspection by a certified organization (e.g., TSSA, ABSA). The conformity assessment route includes:
- Design Review: Submission of design calculations, material test reports, and welding procedure specifications (WPS).
- Fabrication Inspection: Witness of hydrostatic test and NDE by the inspector at hold points.
- Final Certification: Issuance of a Canadian Registration Number (CRN) or a Certificate of Design Accreditation (CDA) as applicable.
The standard includes a grandfathering clause (Clause 5.6) for tanks designed to previous editions (HPIT 1-2012 or HPIT 2-2014) provided they meet pressure-retention safety requirements.
Important: Tanks used in sour service (NACE MR0175/ISO 15156) must also comply with the additional sulfide stress cracking (SSC) requirements of CSA HPIT 2-2017 Annex C.
Frequently Asked Questions
Q: What is the difference between CSA HPIT 2-2017 and ASME Section VIII Division 1?
A: While CSA HPIT 2-2017 borrows many design formulas from ASME VIII-1, it introduces stricter toughness criteria for low-temperature service (MDMT down to -30°C vs. -20°C in ASME) and mandates 100% radiography for all butt welds regardless of joint efficiency. It also requires registration with a Canadian provincial authority.
A: While CSA HPIT 2-2017 borrows many design formulas from ASME VIII-1, it introduces stricter toughness criteria for low-temperature service (MDMT down to -30°C vs. -20°C in ASME) and mandates 100% radiography for all butt welds regardless of joint efficiency. It also requires registration with a Canadian provincial authority.
Q: Can existing tanks be retrofitted to comply with this standard?
A: Yes, the standard provides a rerating procedure (Clause 8) for existing tanks that were not originally built to HPIT 2. However, the rerating is limited to reductions in MAWP or temperature, and the tank must pass a modified hydrostatic test and full UT thickness gauging.
A: Yes, the standard provides a rerating procedure (Clause 8) for existing tanks that were not originally built to HPIT 2. However, the rerating is limited to reductions in MAWP or temperature, and the tank must pass a modified hydrostatic test and full UT thickness gauging.
Q: Does the standard cover composite overwrapped pressure vessels (COPVs)?
A: No. CSA HPIT 2-2017 exclusively addresses all-steel and steel-lined vessels. COPVs fall under CSA HPIT 4-2021. For a composite vessel containing a high-pressure intensifier, you should consult CSA HPIT 4.
A: No. CSA HPIT 2-2017 exclusively addresses all-steel and steel-lined vessels. COPVs fall under CSA HPIT 4-2021. For a composite vessel containing a high-pressure intensifier, you should consult CSA HPIT 4.
Q: Are there any exemptions for very small tanks?
A: Tanks with a volume less than 40 L or an internal diameter below 150 mm are exempt from the full design review, but they must still meet the material and hydrostatic test requirements (Clause 1.2).
A: Tanks with a volume less than 40 L or an internal diameter below 150 mm are exempt from the full design review, but they must still meet the material and hydrostatic test requirements (Clause 1.2).
© 2026 International Standards Publishing. Document reference: CSA HPIT 2-2017 (2026 Edition). All rights reserved.