ASTM A387 Grade 21 Class 1 Steel Plate | A387 Gr.21 Cl.1 3Cr-1Mo Vessel Plate

ASTM A387 Grade 21 Class 1, also searched as A387 Gr.21 Cl.1, A387GR21CL1, A387GR21 CL1, A387GR.21 Class 1, A387-21 Cl.1 and SA387 Grade 21 Class 1, is the lower-strength class of Grade 21 in ASTM A387/A387M. The book is chromium-molybdenum plate for welded boilers and elevated-temperature vessels. Nominal alloy is 3.00Cr-1.00Mo. This page is not Class 2. Class 2 is 515–690 MPa. This page is not ASME SA387 Grade 21L Class 1. Grade 21L is the low-carbon sister. This page is not ASME SA387 Grade 22 Class 1. Grade 22 is 2.25Cr-1Mo. This page is not ASME SA387 Grade 11 Class 1. Grade 11 is 1.25Cr-0.5Mo.

Tensile is 60–85 ksi / 415–585 MPa. Yield is 30 ksi / 205 MPa min. Delivery is thermally treated: annealed, normalized and tempered, or accelerated cooling plus temper. Minimum temper for Grade 21 is 1250 °F / 675 °C. SHH STEEL is a global steel mill sourcing partner and steel manufacturer & exporter (mill-direct, China origin). We buy this grade from qualified Chinese mills, check the certificate against A387 / SA-387 and A20 / SA-20, and ship it to fabricators in the USA, Europe, Middle East, Southeast Asia, Africa and South America.

If a drawing says A387 Gr.21 Cl.2, we will not ship Class 1 and call 415 enough. For ASME Code work the name on the certificate should be SA-387 Grade 21 Class 1. Related category pages: ASTM A387 and ASME SA387.

This plate sits in pressure vessel steel plates and ASTM A387. European Cr-Mo sisters belong on EN 10028-2. Chinese Cr-Mo sisters belong on GB/T 713.

Heat analysis and product analysis follow ASTM A387 Table 1 for Grade 21. Class 1 and Class 2 share the same chemistry.

Heat Analysis and Product Analysis — ASTM A387 Grade 21

Grade 21L limits carbon lower. Do not treat a Grade 22 heat as Grade 21. Grade 22 chromium is 2.00–2.50%. SHH STEEL prints heat analysis on every certificate and product analysis when ordered. Density is 7.85 g/cm³.

Buyers search A387 Gr.21 Cl.1 mechanical properties, A387GR21CL1 yield and A387 Grade 21 Class 1 tensile.

Tensile and Yield — ASTM A387 Grade 21 Class 1

Class 2 on the same grade is 75–100 ksi / 515–690 MPa with 45 ksi / 310 MPa yield. Do not quote Class 2 numbers on a Class 1 order.

There is no official one-to-one worldwide swap for A387 Gr.21 Cl.1. What buyers compare is the 3Cr-1Mo idea in other books, not an automatic substitute.

In the United States the Code name is ASME SA-387 Grade 21 Class 1. That is the same chemistry and the same Class 1 tensile table. ASTM A387 Grade 21 Class 2 is the same chemistry at the higher strength class. ASME SA387 Grade 21L Class 1 is the low-carbon sister, Class 1 only. ASME SA387 Grade 22 Class 1 is 2.25Cr-1Mo, not 3Cr.

In Europe there is no daily 3Cr-1Mo twin in EN 10028-2. 10CrMo9-10 is 2.25Cr-1Mo. 12CrMoV12-10 is about 3Cr-1Mo-V, which is a vanadium grade, not Grade 21. Both sit on EN 10028-2.

In China GB/T 713 12Cr2Mo1R is 2.25Cr-1Mo, closer to Grade 22 than Grade 21. See 12Cr2Mo1R.

Dual marking is possible only when both books are fully met.

Buyers pick A387 Gr.21 Cl.1 when a file wants 3Cr-1Mo at the Class 1 strength band. Search phrases such as A387GR21CL1, A387 Grade 21 Class 1 and SA387 Grade 21 Class 1 all point here.

It is not a substitute for ASME SA387 Grade 22 Class 1. That grade is 2.25Cr. It is not a substitute for ASME SA387 Grade 5 Class 1. That grade is 5Cr-0.5Mo. Dual marking with SA-387 Grade 21 Class 1 is the normal Code route.

SHH STEEL supplies this plate to fabricators in the United States, Mexico, South America, Europe, the Middle East, Africa and Asia.

A387 Grade 21 Class 1 is killed 3Cr-1Mo vessel plate. Treat welding as production welding, and as ASME Section VIII / PED welding when the equipment is a vessel.

Qualify to the applicable code. Consumables must match a 3Cr-1Mo family. A procedure written for ASME SA516 Grade 70 is the wrong alloy. A procedure written for ASME SA387 Grade 22 Class 2 is close on molybdenum but lean on chromium. Preheat, interpass and PWHT must stay inside the qualified WPS. Minimum temper on the plate is 675 °C. The fabricator owns the WPS. SHH STEEL can share mill heat data for that review.

Usual delivery from SHH STEEL for A387 Gr.21 Cl.1 is annealed or normalized and tempered. Accelerated cooling plus temper is allowed when the mill route needs it. Minimum tempering temperature for Grade 21 is 1250 °F / 675 °C.

Class 2 tensile values are not applicable to annealed plate. If the drawing says Class 2, do not ship an annealed Class 1 heat and call it close.

If the vessel will see PWHT, say so. Simulated PWHT on test coupons is worth naming on 3Cr-1Mo work. Extra simulation, 3.2 hold points or special NDE add time. Plan about two months when those extras are on the order.

The certificate lists ASTM A387 Grade 21 Class 1 and, when ordered, ASME SA-387 Grade 21 Class 1; heat number; heat analysis; product analysis when ordered; tensile to the Class 1 table; heat-treatment route. Certificates may be EN 10204 3.1 or EN 10204 3.2.

Usual supply range from SHH STEEL for A387 Gr.21 Cl.1 3Cr-1Mo vessel plate:

• Thickness: commonly 6 mm – 200 mm, thicker by mill agreement
• Width: 1500 mm – 4000 mm
• Length: 3000 mm – 12000 mm

Maximum thickness is limited by the ability of the composition to meet Class 1 tensile. 2.25Cr-1Mo plate belongs on ASME SA387 Grade 22 Class 1. 5Cr plate belongs on ASME SA387 Grade 5 Class 1.

Dimensional limits for ASTM A387 Grade 21 Class 1 follow ASTM A20 / ASME SA-20 unless the purchase order names another table. Do not apply ASTM A36 structural tolerances to a Cr-Mo vessel plate without writing them.

Typical thickness tolerance idea for A387 Gr.21 Cl.1 (A20 / SA-20 reference)

Width on 1500–4000 mm plate is commonly held to about ±20–25 mm unless the mill quote names a tighter extra. Length on 3000–12000 mm plate is commonly held to about +50 / 0 mm or ±25 mm by mill practice. Flatness follows A20 / SA-20 unless a tighter class is written. Edge condition is mill edge or cut edge as ordered. If the vessel calculation used minimum thickness after corrosion, write the allowed minus on the RFQ. SHH STEEL will not assume a zero-minus extra on A387GR21CL1 unless the order says so.

ASTM A387 Grade 21 Class 1 already defines chemistry, Class 1 tensile and the 675 °C minimum temper. Extra items still have to be written on the purchase order. SHH STEEL will not assume them from the grade name alone.

Code name. Write SA-387 Grade 21 Class 1 when the equipment is ASME Code work.

Heat-treatment route. Write annealed, normalized and tempered, or accelerated cooling plus temper. Do not leave it as “as-rolled.”

Charpy details. Class 1 does not assume a default impact temperature. Write temperature, joules, location and orientation if impact is required.

Simulated PWHT. When the vessel will be stress-relieved, name hold temperature, hold time and cooling rate on the coupon.

Product analysis. Especially C, Cr, Mo, P and S.

Through-thickness / Z-test. Name Z15, Z25 or Z35 when the plate will be welded in the thickness direction.

NDE. A20 / SA-20 ultrasonic extras, ASTM A435 or ASTM A578 as named. Write scanning extent and acceptance class.

Hardness. If the destination file caps hardness after heat treatment or after simulated PWHT, write the max HB and the test location.

HIC / SSC / NACE. Only when the equipment is sour service. A387 Gr.21 Cl.1 is not automatically NACE MR0175 / ISO 15156.

Third-party witness. EN 10204 3.2 with SGS, TÜV, BV, ABS, CCS, DNV or the inspector named. Hold points for heat treatment, chemistry, tensile and UT should be listed on the ITP.

Identification and stamping. Heat number, grade A387 Grade 21 Class 1 / A387 Gr.21 Cl.1, SA-387 Grade 21 Class 1 when ordered, thickness and mill logo on each plate.

A387 Grade 21 Class 1 is the plate for a file that wants 3Cr-1Mo at the lower strength class. It is the wrong plate for Class 2 tensile. That work is A387 Grade 21 Class 2. It is the wrong plate for 9Cr-1Mo-V. That work is ASME SA387 Grade 91 Class 2.

SHH STEEL sources ASTM A387 Grade 21 Class 1 from first-line Chinese mills and ships it on worldwide terms. Partner mills include Wuyang (Wugang), Angang, Shougang, Hanye, Anyang Iron & Steel, Baosteel, Xinyu, Xingcheng, Yongjin, Tsingshan, TISCO (Taiyuan), Jiuquan (JISCO), Lianzhong, Zhangpu and Baoxin, plus other qualified mills when the size or heat-treatment route requires it.

Mill test certificates are issued to EN 10204 3.1 as standard. EN 10204 3.2 is arranged when the order names a third-party hold point.

Usual stock and rolling thickness: 8 mm, 10 mm, 12 mm, 16 mm, 20 mm, 25 mm, 30 mm, 32 mm, 36 mm, 40 mm, 50 mm, 60 mm, 80 mm, 100 mm, 120 mm, 150 mm, thicker by mill agreement.

Processing: CNC or flame cutting, bevel, flattening, UT to the named class.

Trade terms: FOB Shanghai main, CIF destination available. Payment: TT, LC, or TT + LC.

Ocean time from Shanghai: US West 14–18 days; US Gulf 28–35 days; Rotterdam / Antwerp 28–35 days; Jebel Ali 18–25 days; Singapore 7–12 days; other ports quoted.

Third-party: SGS, TÜV, BV, ABS, CCS, GL, VL, DNV, RINA, NK, KR, or the inspector named.

SHH STEEL is a global steel mill sourcing partner with mill partnerships in China. We supply ASTM, ASME, EN, DIN, JIS and GB steel to buyers in the United States, Europe, the Middle East, Southeast Asia, Africa and South America. Origin is mill-direct, China origin.

SHH STEEL has supplied steel plates to the USA, Mexico, Argentina, Peru, El Salvador, Spain, Netherlands, Germany, UAE, Saudi Arabia, South Africa, India, Thailand, Singapore, Vietnam, the Philippines, Japan and Korea.

Typical lead time: ex-stock 5–7 days; standard rolling / heat treatment about 45–60 days; simulated PWHT / 3.2 about 2 months.

Experience on this grade is simple: keep Grade 21 away from Grade 22 and Grade 21L, and keep Class 1 away from Class 2. SHH STEEL as a global steel mill sourcing partner and steel manufacturer & exporter (mill-direct, China origin) prices A387 Gr.21 Cl.1 from first-line mills, reports 3Cr-1Mo chemistry, records annealed or N+T delivery, and issues 3.1 as standard or 3.2 when specified.

We keep the grade on the order. A387GR21CL1 is not A387 Gr.21 Cl.2. A387 Grade 21 Class 1 is not ASME SA387 Grade 21L Class 1. A387 Gr.21 Cl.1 is not ASME SA387 Grade 22 Class 1. If the drawing says Class 2, we will not ship Class 1 and call 415 close.

ASTM A387 Grade 21 Class 1 Steel Plate is 3Cr-1Mo pressure-vessel plate at 415–585 MPa tensile and 205 MPa yield. Whether the inquiry says ASTM A387 Grade 21 Class 1, A387 Gr.21 Cl.1, A387GR21CL1, A387GR21 CL1 or SA387 Grade 21 Class 1, SHH STEEL as a global steel mill sourcing partner and steel manufacturer & exporter (mill-direct, China origin) supplies plate with Grade 21 chemistry, Class 1 tensile, recorded heat treatment, and EN 10204 3.1 or 3.2 certification.

SHH STEEL supplies ASTM A387 Grade 21 Class 1 / A387 Gr.21 Cl.1 3Cr-1Mo Vessel Plate to the USA, Mexico, South America, Europe, the Middle East, Africa and Asia for work that actually names this grade and class.

Contact SHH STEEL for mill rolling, stock inquiry, cutting, bevel, 3.2 inspection or a worldwide quotation.

ASTM A387 Grade 21 Class 1 Steel Plate, A387 Gr.21 Cl.1, A387GR21CL1, 3Cr-1Mo vessel plate, A387 Gr.21 Cl.1 supplier, SHH STEEL