Dimensions / Building materials / Bricks / Firebrick
Firebrick follows the 9-inch series, not the 4 in brick module. The standard straight is 9 × 4-1/2 × 2-1/2 in, and its volume of 101.25 in³ is the nine-inch equivalent by which refractories are counted; HarbisonWalker calls 9 × 4-1/2 × 3 in the most widely used size. A split halves the thickness to 1-1/4 in, a soap halves the width to 2-1/4 in. Fireclay brick is classed by its PCE cone: super duty 33 or higher, high duty 31-1/2, medium 29, low 15. Round linings use tapered shapes: 76 No. 1 arch close a ring 4’3” across inside. China’s standard brick is 230 × 114 × 65 mm.
| Straight, one nine-inch equivalent: length; width × thickness (HarbisonWalker) | Most widely used size: length; width × thickness (HarbisonWalker) | China standard brick: length; width × thickness (GB/T 2992.1-2011) |
|---|---|---|
| 9in4-1/2 × 2-1/2 in | 9in4-1/2 × 3 in | 230mm114 × 65 mm |
Sources: HarbisonWalker, GB/T 2992.1. Checked October 2026.
A 4-1/2 in lining of 9-inch straights and a 36 in ring are filled in. Enter your lining, the ring and the PCE cone on the data sheet; each check follows a figure or rule on this page.
Counts leave out the thin joints. Rings use the HarbisonWalker taper shapes. The PCE cone is on the supplier’s data sheet.
40 sq ft of 4-1/2 in lining in 9 × 4½ × 2½ in brick, at 6.4 a sq ft, is 256; with 5% waste you need 269 bricks, 269 nine-inch equivalents. 300 ordered covers it.
A 9 × 4-1/2 × 2-1/2 in straight is one nine-inch equivalent, 101.25 in³; the 40 sq ft lining and 5% waste are examples.
A ring 36 in across inside with a 4-1/2 in lining takes 38 No. 1 arch + 19 No. 2 arch; 10 rings take 380 No. 1 arch + 190 No. 2 arch.
HarbisonWalker’s ring table: a 36 in ring in a 4-1/2 in lining takes 38 No. 1 arch and 19 No. 2 arch.
Medium duty needs PCE cone 29 or higher; cone 31 meets it (medium duty).
HarbisonWalker puts medium duty at PCE cone 29 to 31–31-1/2; Alsey’s Smithfield medium duty brick tests PCE 29.
Selling firebrick? Photograph a straight and its shapes, mark the size, the taper, the duty class and the PCE in SizeMarker and send it with your quote.
Mark a photoFirebrick quantities are counted in nine-inch equivalents, the volume of a 9 × 4-1/2 × 2-1/2 in straight.
| Shape | Size, in | Nine-inch equivalents |
|---|---|---|
| StraightThis page | 9 × 4-1/2 × 2-1/2 (101.25 in³) | 1.00 |
| 3 in straight | 9 × 4-1/2 × 3, the most widely used size | 1.20 |
| Soap | 9 × 2-1/4 × 2-1/2 | 0.50 |
| Split | 9 × 4-1/2 × 1-1/4 | 0.50 |
| 2 in split | 9 × 4-1/2 × 2 | 0.80 |
| No. 1-X, 1, 2 wedge | 9 × 4-1/2, thickness 2-1/2 tapering to 2-1/4, 1-7/8, 1-1/2 end to end | 0.95, 0.88, 0.80 |
| No. 1, 2, 3 arch | 9 × 4-1/2, thickness 2-1/2 tapering to 2-1/8, 1-3/4, 1 edge to edge | 0.93, 0.85, 0.70 |
| No. 1 to 4 key | 9 × 2-1/2, width 4-1/2 tapering to 4, 3-1/2, 3, 2-1/4 | 0.94, 0.89, 0.83, 0.75 |
Sources: HarbisonWalker
Maker data sheets; values are typical test data, not guarantees.
| Brick | Sizes | Class; PCE | Service temperature; density |
|---|---|---|---|
| Alsey Pilot D.P.This page | 9 × 2-1/4 × 2-1/2 soap, 9 × 4-1/2 × 1-1/4 split, 9 × 4-1/2 × 2-1/2 and 9 × 4-1/2 × 3 in straights | Super duty; PCE 33 | Up to 2910 °F; 139 lb/ft³ |
| Alsey Jet D.P. | The same four sizes | High duty; PCE 32–32-1/2 | Up to 2850 °F; 133.7 lb/ft³ |
| Alsey Smithfield | The same four sizes | Medium duty; PCE 29 | Up to 2700 °F; 130.2 lb/ft³ |
| Alsey Exeter 90 | Various sizes | High alumina, 90.3% Al₂O₃; PCE over 40 | Up to 3300 °F; 184.8 lb/ft³ |
| Whitacre Greer buff | Splits 9 × 4-1/2 × 1-1/4 in, 850 a pallet; soaps 9 × 2-1/4 × 1-1/4 in, 1416 a pallet | ASTM C27 low duty and C1261; PCE 15 | Up to 2000 °F |
| Whitacre Greer red | The same sizes | C1261; PCE 13 | Up to 1750 °F |
| Morgan JM23, JM26, JM28, JM30Insulating firebrick | — | Classification 2300, 2600, 2800 and 3000 °F (1260, 1430, 1540, 1650 °C) | 480, 800, 890 and 1020 kg/m³ |
| Allied Mineral AMPBNZ insulating firebrick | 9 × 4.5 × 2.5 in, 12 a carton; 9 × 4.5 × 3 in, 10; 13.5 × 4.5 × 3 in, 8 | AMP-23 2300 °F, AMP-26 2600 °F (ASTM grade 26), AMP-28 2800 °F | — |
| Zhengzhou Rongsheng T-3China | 230 × 114 × 65 mm | Clay firebrick | — |
Sources: Alsey · Alsey · Alsey · Alsey · Alsey · Whitacre Greer · Whitacre Greer · Whitacre Greer · Morgan Thermal Ceramics · Allied Mineral · Zhengzhou Rongsheng
| Class | Figure |
|---|---|
| Super dutyHarbisonWalker | PCE cone 33 or higher |
| High dutyHarbisonWalker | PCE cone 31-1/2 to 32-1/2–33 |
| Medium dutyHarbisonWalker | PCE cone 29 to 31–31-1/2 |
| Low dutyHarbisonWalker | PCE cone 15 to 28–29 |
| Semi-silicaHarbisonWalker | Fireclay brick with at least 72% silica |
| Super duty, spall resistantNY State OGS | PCE 33; at most 4% spalling loss at 3000 °F, 1% reheat shrinkage at 2910 °F; at least 600 psi modulus of rupture |
| Insulating firebrick, group 26NY State OGS | At most 2% reheat change at 2550 °F, at most 54 lb/ft³ |
| FireplacesBIA TN 19 | ASTM C27 low duty firebrick allows a thinner firebox wall; joints not over 1/4 in |
| ChinaGB/T 2992.1-2011 | Standard brick 230 × 114 × 65 mm (or 75 mm); the T-3 name is from the older GB/T 2992-1998 |
Sources: HarbisonWalker · NY OGS · BIA · GB/T 2992.1 · SAMR
| Item | Figure |
|---|---|
| Arch ring, 4-1/2 in liningHarbisonWalker | No. 1 arch: 76 a ring, 4’3” across inside; No. 2: 38, 1’9”; No. 3: 19, 6 in |
| Wedge ring, 9 in liningHarbisonWalker | No. 1 wedge: 91 a ring, 4’6” across inside; No. 2: 57, 2’3” |
| Two shapesHarbisonWalker | A 36 in ring in a 4-1/2 in lining: 38 No. 1 arch and 19 No. 2 arch, as HarbisonWalker’s table prints it |
| Arch or wedgeHarbisonWalker | An arch tapers edge to edge and makes a 4-1/2 in lining; a wedge tapers end to end and makes a 9 in lining |
| CountingHarbisonWalker | A fraction of a tenth of a brick or more counts as a whole brick |
| Bricks a sq ft of wallHarbisonWalker | 9 × 4-1/2 × 3 in brick: 5.3 in a 4-1/2 in wall, 10.7 in 9 in, 16.0 in 13-1/2 in |
| JointsBIA TN 19A | Fireclay mortar joints 1/16–3/16 in |
| MortarHarbisonWalker | SATANITE: 250–300 lb per 1000 nine-inch brick laid dry or grouted, 350–450 lb dipped |
| China jointsGB 50211-2014 | Special class up to 0.5 mm, class I 1 mm, II 2 mm, III 3 mm, class IV over 3 mm |
| EuropeDIN 1082-1 | Arch formats 250 and 124 mm long, and the widespread 230, 172 and 114 mm |
| In the check aboveOur calculation | 144 × 4-1/2 ÷ 101.25 = 6.4 a sq ft; 40 sq ft = 256 + 5% = 268.8, so 269 bricks; the 36 in ring: 38 + 19, 380 + 190 for 10 rings; PCE 31 meets medium duty |
Sources: HarbisonWalker · BIA · GB 50211 · DIN
The standard straight is 9 × 4-1/2 × 2-1/2 in, the nine-inch equivalent of 101.25 in³ by which refractories are counted; HarbisonWalker calls 9 × 4-1/2 × 3 in the most widely used size. Splits are 9 × 4-1/2 × 1-1/4 in and soaps 9 × 2-1/4 × 2-1/2 in. China’s standard brick is 230 × 114 × 65 mm.
The PCE, the pyrometric cone the brick matches before it softens: super duty cone 33 or higher, high duty 31-1/2 and up, medium duty 29 to 31–31-1/2, low duty 15 to 28–29 (HarbisonWalker). Alsey rates its super duty Pilot up to 2910 °F and its medium duty Smithfield up to 2700 °F.
It depends on the shape and the diameter: in a 4-1/2 in lining, 76 No. 1 arch close a ring 4’3” across inside, and a 36 in ring takes 38 No. 1 and 19 No. 2 arch (HarbisonWalker). The check above works any diameter from the same formula.
Thin: 1/16–3/16 in for fireclay mortar in a fireplace (BIA Technical Note 19A), and not over 1/4 in. China’s GB 50211 sorts furnace linings by joint, from 0.5 mm for the special class to over 3 mm for class IV.
Light refractory bricks graded by group: Morgan’s JM23 classifies at 2300 °F and weighs 480 kg/m³, JM30 3000 °F and 1020 kg/m³, against 139 lb/ft³ for Alsey’s dense super duty brick. Allied Mineral packs its 9 × 4.5 × 2.5 in insulating firebrick 12 to a carton.
Buyers ask for the size and shape (straight, split, arch, wedge, key) and its number, the duty class or alumina content, the PCE and the maximum service temperature, the density and porosity, the cold crushing strength, the matching mortar, and pieces and weight per pallet or carton. Mark them on a photo of your own brick in SizeMarker, as in the picture at the top, and send one product card for WhatsApp or WeChat.
