SPV490
High-strength weldable steel plate for pressure vessels and high-pressure equipment · JIS G 3115:2022 — Steel plates for pressure vessels for intermediate temperature service · JIS G 3193 — Dimensional and tolerance requirements for hot-rolled steel plate · JIS G 0404 — General technical delivery requirements for steel products
SPV490 is the highest-strength grade in JIS G 3115:2022, intended for welded pressure vessels and high-pressure equipment outside explicitly high- or low-temperature service. It combines a 490 MPa minimum yield or proof strength at plate thicknesses up to 50 mm with 610–740 MPa tensile strength and specified Charpy toughness at −10 °C. It is normally supplied quenched and tempered, and its specification, welding procedure and certification must preserve the applicable heat-treatment condition, thickness-dependent strength and weldability limits.
- Hot-rolled plate, 6–150 mmApplicable product and thickness · JIS G 3115 does not define SPV490 bar, forging, pipe or casting products.
- Quenched and tempered (SPV490Q)Normal delivery condition · Normalized supply is possible only by purchaser–manufacturer agreement.
- 490 MPa at 6–50 mmMinimum yield or proof strength · Decreases to 470 MPa above 50–100 mm and 450 MPa above 100–150 mm.
- 610–740 MPaTensile strength · Applies throughout the specified 6–150 mm thickness range.
- 47 J average at −10 °CStandard impact requirement · Longitudinal full-size V-notch specimens; each individual result must be at least 27 J.
- Thickness-dependent JIS Ceq or agreed Pcm limitWeldability control · The JIS carbon-equivalent equation is not the conventional IIW CEV equation.
Overview
- Designation system
- Japanese Industrial Standard grade under JIS G 3115
- Product forms
- Hot-rolled steel plate
- Condition
- Quenched and tempered (Q) — standard production route for SPV490, Normalized (N) — permitted by agreement between purchaser and manufacturer, As-rolled plate with separately normalized or quenched-and-tempered test material — permitted by agreement when the heat, treatment is to be performed by the purchaser, Test material may additionally receive simulated post-weld heat treatment (SR) when specified
What the designation covers
JIS G 3115 covers weldable hot-rolled steel plates for pressure vessels and high-pressure equipment, excluding applications explicitly treated as high- or low-temperature service. SPV490 is a strength-based plate designation rather than a single fixed alloy recipe. The number 490 corresponds to the minimum yield point or proof stress for plate up to 50 mm thick; it does not denote tensile strength.
Compliance with JIS G 3115 establishes material delivery requirements, not pressure-vessel design approval. The applicable construction code must separately establish allowable stress, minimum design metal temperature, welding qualification, heat treatment, examination and service restrictions.
Heat-treatment condition and suffixes
SPV490 is normally produced by quenching and tempering. Normalizing may replace quenching and tempering only by agreement. The delivery condition is therefore part of the material identity and must appear in the purchase documentation and plate marking. A certificate for SPV490Q must not be treated as interchangeable with one for SPV490N or with an as-rolled plate represented by separately heat-treated test material.
| Suffix | Meaning | Practical significance |
|---|---|---|
| Q | Plate quenched and tempered | Normal production condition for SPV490. |
| N | Plate normalized | Allowed by agreement; weldability limits for normalized SPV490 are also subject to agreement. |
| TN | Plate supplied as rolled; test material normalized | Used when the purchaser will perform the specified plate heat treatment. |
| TQ | Plate supplied as rolled; test material quenched and tempered | Represents an agreed purchaser heat-treatment route. |
| SR | Test material receives heat treatment simulating post-weld heat treatment | May be combined with a plate or test-material condition; the number before SR denotes repeated cycles, for example 2SR. |
| Example: SPV490TQ2SR | As-rolled plate; test material quenched and tempered and given two simulated PWHT cycles | The represented fabrication history must match the ordering agreement. |
Test-material simulation does not by itself define an acceptable fabrication PWHT temperature, holding time or heating rate; those remain construction-code and procedure matters.
Chemical composition and weldability controls
| Element | Requirement, mass % | Comment |
|---|---|---|
| C | ≤ 0.18 | Maximum carbon content. |
| Si | ≤ 0.75 | No minimum is specified. |
| Mn | ≤ 1.60 | No minimum is specified. |
| P | ≤ 0.020 | Maximum phosphorus. |
| S | ≤ 0.020 | Maximum sulfur. |
Other alloying elements may be added as necessary. For normalized SPV490, additions of elements not listed in the table are subject to purchaser–manufacturer agreement. Consequently, the five-element table is not a complete description of the alloy system.
Weldability is controlled primarily by a JIS carbon equivalent calculated from the complete cast analysis. By agreement, the weld-crack sensitivity composition Pcm may be used instead. The purchase specification and inspection certificate should make clear which criterion applies. Values calculated using other carbon-equivalent equations must not be substituted without technical review.
| Nominal plate thickness | Maximum Ceq |
|---|---|
| 6–50 mm | 0.45% |
| >50–75 mm | 0.47% |
| >75–100 mm | 0.50% |
| >100–125 mm | 0.53% |
| >125–150 mm | 0.55% |
For normalized SPV490, the carbon-equivalent requirement is established by agreement.
| Nominal plate thickness | Maximum Pcm |
|---|---|
| 6–50 mm | 0.28% |
| >50–150 mm | 0.30% |
For normalized SPV490, the Pcm requirement is established by agreement.
Mechanical properties
| Nominal plate thickness | Minimum yield point or proof stress | Tensile strength |
|---|---|---|
| 6–50 mm | 490 MPa | 610–740 MPa |
| >50–100 mm | 470 MPa | 610–740 MPa |
| >100–150 mm | 450 MPa | 610–740 MPa |
Tensile and bend specimens are taken transverse to the final rolling direction. Strength must not be specified as 490 MPa without checking the ordered thickness.
| Plate thickness | JIS tensile specimen | Minimum elongation |
|---|---|---|
| 6–16 mm | No. 5 | 18% |
| >16–20 mm | No. 5 | 25% |
| >20–150 mm | No. 5 | 25% |
| >20–150 mm, where No. 4 specimen is used | No. 4 | 19% |
Elongation values are specimen-dependent and should not be compared without preserving specimen type and gauge geometry.
| Bend angle | Inside radius | Specimen | Acceptance |
|---|---|---|---|
| 180° | 1.5 × plate thickness | JIS No. 1 | No cracking on the outside of the bend |
The manufacturer may omit routine bend testing, but the material must still satisfy the requirement. Testing becomes mandatory when specifically ordered.
Charpy toughness and test orientation
For plate thicker than 12 mm, Charpy testing is a standard requirement. Full-size V-notch specimens are normally oriented longitudinally, with their axis parallel to the final rolling direction, and are taken near the quarter-thickness and quarter-width positions. Transverse testing or a lower test temperature may be agreed; if transverse testing is agreed, the purchaser may approve omission of the longitudinal test.
| Test temperature | Direction | Average of three specimens | Minimum individual result |
|---|---|---|---|
| −10 °C | Longitudinal | ≥ 47 J | ≥ 27 J |
A lower test temperature may replace −10 °C by agreement. This does not automatically establish suitability at that temperature under a particular pressure-vessel code.
| Difference between plate and specimen thickness | 10 × 10 mm | 10 × 7.5 mm | 10 × 5 mm |
|---|---|---|---|
| ≤ 3 mm: average of three | 47 J | 35 J | 24 J |
| ≤ 3 mm: individual minimum | 27 J | 22 J | 14 J |
| > 3 mm: average of three | 47 J | 39 J | 31 J |
| > 3 mm: individual minimum | 27 J | 23 J | 19 J |
For plate 12 mm or thinner, impact testing is performed only when specified at ordering.
Welding and fabrication implications
SPV490 is designed for welded pressure equipment, but its relatively high strength and thickness-dependent Ceq or Pcm make hydrogen control, joint restraint and heat input important. JIS G 3115 does not provide universal preheat, interpass-temperature or heat-input values. These must be established through the applicable construction code and qualified welding procedure using the actual plate thickness, certificate chemistry, consumable, joint geometry and hydrogen level.
| Issue | Practical treatment |
|---|---|
| Filler-metal selection | Japanese Welding Engineering Society guidance groups SPV410, SPV450 and SPV490 with 570–590 MPa-class high-strength-steel consumables. Final selection must satisfy the qualified procedure, weld-metal strength and required toughness. |
| Hydrogen-assisted cracking | Use controlled low-hydrogen consumables and appropriate storage, drying, preheat and interpass controls. Requirements depend on chemistry, thickness, restraint and process. |
| Heat input | Maintain the qualified range needed to achieve weld and heat-affected-zone properties. Do not assume that a procedure qualified on a lower-strength SPV grade transfers to SPV490. |
| Post-weld heat treatment | If PWHT is expected, order material with a representative SR test simulation where required. Repeated repair or PWHT cycles may need to be represented by multiple SR cycles. |
| Cold or hot forming | Account for the quenched-and-tempered condition and subsequent thermal history. Forming and any restoration heat treatment must follow an approved procedure rather than generic carbon-steel practice. |
| Thermal cutting and weld repairs | Use procedures compatible with high-strength plate. Weld repair of plate surface defects by the steelmaker requires prior purchaser approval under JIS G 3115. |
The grade's specified Ceq or Pcm is a material-control parameter, not a complete welding procedure.
Inspection, dimensions and purchasing
The dimensional basis is JIS G 3193 with additional JIS G 3115 plate-thickness tolerances. The standard negative thickness tolerance is 0.25 mm. If zero negative tolerance is agreed, 0.25 mm is added to the applicable positive tolerance. Cut-edge width uses tolerance class A, and length uses the JIS G 3193 length tolerance A unless otherwise agreed.
| Item | Why it matters |
|---|---|
| Standard and edition | State JIS G 3115:2022; older certificates may reflect different editions. |
| Complete grade and condition | Normally SPV490Q; identify normalized or purchaser-heat-treated routes explicitly. |
| Dimensions and tolerances | State thickness, width, length, edge condition and any requirement for zero negative thickness tolerance. |
| Represented fabrication heat treatment | Specify TN, TQ, SR and number of simulated PWHT cycles where applicable. |
| Impact testing | For ≤12 mm plate, testing must be ordered. State any lower temperature or transverse orientation requirement. |
| Weldability criterion | Confirm whether JIS Ceq or agreed Pcm applies; normalized plate requires agreed limits. |
| Ultrasonic examination | Not an automatic JIS G 3115 requirement. Agree the method, coverage and acceptance criteria, commonly with reference to JIS G 0801. |
| Inspection document | Unless otherwise specified, the standard calls for a JIS G 0415 inspection certificate 3.1. |
| Additional construction-code requirements | Identify supplementary testing, through-thickness properties, PWHT simulation, NDE, toughness or certification required by the vessel code or project specification. |
The inspection certificate should report added alloying elements where applicable. When Ceq or Pcm is applied, the analysis values for all elements included in the selected equation must be reported so the calculation can be verified.
Limits on substitution
Substitution cannot be based on nominal yield strength alone. A candidate material must be reviewed for its governing product standard, heat-treatment route, thickness range, tensile-strength band, impact-test temperature and orientation, chemistry and weldability equation, PWHT response, inspection requirements, certification and acceptance under the applicable pressure-equipment code. JIS G 3115 is technically modified from the referenced ISO 9328 standards, so an ISO or EN grade associated with SPV490 in a comparison table is not automatically identical or interchangeable.
Sources
- JIS G 3115:2022 — Steel plates for pressure vessels for intermediate temperature serviceJapanese Standards Association
- JIS G 3115:2022 English previewJapanese Standards Association
- Draft for revision of JIS G 3115 — 2021 Steel Standards Tripartite Committee Material 8Japan Iron and Steel Federation
- Welding consumable selection and precautions for JIS G 3115 SPV steelsJapan Welding Engineering Society, Welding Information Center
- ISO 9328-1:2018 — General technical delivery conditions for pressure-purpose flat productsInternational Organization for Standardization
- ISO 9328-6:2018 — Weldable fine-grain steels, quenched and temperedInternational Organization for Standardization
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