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724L Urea Grade Stainless Steel Forgings
316L Modified, EN 1.4435 (X2CrNiMo18-14-3), UNS S31603. Forged rings, flanges, bars, discs, sleeves, shafts and tube sheets, made to drawing by Jiangyin Jiangnan Metal Co., Ltd.
724L is a urea grade 316L modified austenitic stainless steel with extra-low silicon, a higher molybdenum content than standard 316L, and nickel close to 14 percent. That balance keeps the alloy fully austenitic and free of intermetallic precipitation, with ferrite held below 0.5 percent after solution annealing and water quenching, which is what gives it its resistance in urea and carbamate environments. Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory in Jiangyin, Jiangsu, China, forges 724L to ASTM A182 as rings, flanges, bars, discs, sleeves, shafts, tube sheets and forged pipe, with EN 10204 3.1 or 3.2 certification. Enquiries: sales@steelforgepieces.com, +86-189-2135-9659.
What 724L is and why urea plants specify it
Standard 316L corrodes quickly in hot ammonium carbamate, the aggressive intermediate of the urea synthesis loop. 724L answers that with three changes to the chemistry. Carbon is kept very low so chromium carbides do not precipitate at grain boundaries during welding or sensitisation. Silicon is held well below the normal 316L level. Molybdenum is raised to improve resistance to uniform attack in the reducing carbamate medium. Nickel near 14 percent completes the balance and makes the structure fully austenitic.
For a forging, the microstructure matters as much as the analysis. A delta ferrite stringer in a flange face is a preferential corrosion path, so ferrite is controlled below 0.5 percent in the solution annealed and water quenched condition, and the material is verified by the Huey test to ASTM A262 Practice C rather than by chemistry alone.
Chemical composition of 724L (316L Mod)
| Element | C | Si | Mn | P | S | Cr | Ni | Mo | Fe |
|---|---|---|---|---|---|---|---|---|---|
| Specified range | 0.030 max | 0.50 max | 1.00-2.00 | 0.045 max | 0.030 max | 17.0-18.5 | 13.0-15.0 | 2.00-3.00 | Bal. |
| Typical aim | under 0.030 | under 0.50 | 1.5 | low | low | 18.0 | 13.5-14.0 | 2.6 | Bal. |
Typical aim values follow published urea grade 316L Mod data (C under 0.03, Cr 18, Ni 13.5, Mo 2.6, Si under 0.5, Mn 1 to 2). Ranges are indicative. The purchase order and licensor specification govern, and we confirm the exact analysis to be met before the heat is melted.
Mechanical properties of 724L forgings
| Property | Minimum | Typical |
|---|---|---|
| Tensile strength Rm | 490 MPa (71 ksi) | 530 MPa (77 ksi) |
| Yield strength Rp0.2 | 190 MPa (27 ksi) | 250 MPa (36 ksi) |
| Yield strength Rp1.0 | - | 280 MPa (41 ksi) |
| Elongation A5 | 40 % | 55 % |
| Impact KCV, room temperature | - | about 120 J/cm2 |
| Density | 7.9 kg/dm3 | |
530 MPa and 280 MPa are typical values, not specification minima. Published minima for the grade are 490 MPa tensile and 190 MPa 0.2 percent proof stress at room temperature. Properties of heavy forged sections are confirmed on prolongation test pieces from the actual heat.
Manufacturing route at our works
Melting
724L is melted by EAF plus VOD for clean, low carbon, low silicon chemistry. ESR remelting is available where the customer or licensor requires better homogeneity and lower inclusion content in heavy sections.
Open-die forging
Hot working is carried out in the 1200 to 950 C window from a uniformly heated ingot or billet, with enough forging reduction to break down the cast structure. Rings are produced on a ring rolling mill as seamless rolled rings. Discs, shafts, sleeves and tube sheets are upset and drawn on open dies.
Heat treatment
Solution annealing at 1050 to 1150 C followed by water quenching, which returns all carbides to solution and holds ferrite below 0.5 percent. Where a licensor specification calls for the higher 1120 to 1180 C window used for urea grade plate, we anneal to that requirement instead.
Testing and documents
Ultrasonic examination to EN 10228-3, SEP 1921 or ASTM A388 as specified. Intergranular corrosion testing by the Huey test, ASTM A262 Practice C. PMI, ferrite measurement, mechanical testing and dimensional inspection. Certificates to EN 10204 3.1, or EN 10204 3.2 with third party witness on request.
724L forged products we supply
| Product form | Typical service |
|---|---|
| Seamless rolled rings and forged rings | Reactor and high pressure equipment rings, shell courses, spacer rings |
| Forged flanges, weld neck, blind, long weld neck, orifice | High pressure synthesis loop piping connections |
| Forged round bars, blocks and slabs | Machined fittings, valve components, stock for further machining |
| Forged discs, disks and tube sheets | Carbamate condensers, strippers, heat exchangers |
| Forged bushings and sleeves | Wear and sealing components in corrosive duty |
| Forged shafts, eccentric shafts and spindles | Pumps, agitators, rotating equipment |
| Forged pipe, forged tube and nozzles | High pressure carbamate piping, reactor nozzles, scrubber connections |
| Valve bodies, bonnets, seat rings, valve stems, blocks | Ball, gate, globe, check and plug valves in urea service |
Where 724L forgings are used
724L belongs to the high pressure end of a urea plant. The main applications are the urea synthesis reactor, including lining plates and base material for strip overlay welding, and the high pressure carbamate condensers, strippers, decomposers, separators and scrubbers, together with the piping, fittings and valves of the synthesis loop.
It is not normally specified for low pressure downstream service, where standard 316L is adequate and cheaper, and it is not a nitric acid grade. Buyers also order the same material for adjacent chemical process duty where carbamate or ammonia carryover is present, and for fertilizer plant revamp spares where the original licensor specification has to be matched exactly.
Related grades we forge
If 724L is not the right fit, we also forge A182 F316L and 1.4435 for general corrosion service, A182 F44 and 904L for halide and sulphuric duty, F51 and F53 duplex grades where higher strength is needed, and Sanicro 28 or Alloy 31 for more aggressive environments.
Frequently asked questions about 724L
Is 724L the same as 316L?
No. 724L is a modified version of 316L. It stays in the same 18Cr-14Ni-Mo family but with extra-low silicon, molybdenum at the top of or above the normal 316L band, nickel close to 14 percent, and ferrite held below 0.5 percent. Standard 316L will not reliably survive hot carbamate. 724L is made for it.
What is the equivalent of 724L?
The usual cross references are 316L Modified or 316L UG, EN 1.4435 (X2CrNiMo18-14-3) and UNS S31603. Because 724L is a urea grade designation rather than a single standardised grade, mills publish slightly different cross references, so the licensor specification on your enquiry is what we work to.
What heat treatment do you apply to 724L forgings?
Solution annealing at 1050 to 1150 C followed by water quenching, so all carbides return to solution and the structure stays fully austenitic. Where the specification calls for the 1120 to 1180 C range, we anneal to that instead.
Can you supply a Huey test and third party certification?
Yes. Intergranular corrosion testing by the Huey test to ASTM A262 Practice C is standard for urea grade material, and certificates can be issued to EN 10204 3.1 or 3.2 with third party witness.
What sizes and weights can you forge?
Sizes are confirmed against your drawing. Send the drawing or the outline dimensions, required specification, heat treatment condition, testing scope and quantity, and we will confirm feasibility, weight and lead time.
Who makes 724L urea grade forgings in China?
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province 214423, China, producing 724L rings, flanges, bars, discs, sleeves, shafts and tube sheets for export. Contact sales@steelforgepieces.com or +86-189-2135-9659.
Request a 724L forging quotation
Send your drawing, or the grade, dimensions, specification, heat treatment condition, testing requirements and quantity. Our engineering team replies with feasibility, weight, price and lead time.
Jiangyin Jiangnan Metal Co., Ltd. - Open-Die Forging Factory
No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province 214423, China
Tel / WhatsApp / WeChat: +86-189-2135-9659
E-mail: sales@steelforgepieces.com
Technical data on this page is compiled from published urea grade 316L Mod and EN 1.4435 datasheets and is given for guidance. Actual values are confirmed on the certified test report for each heat.