Sandvik 3R60™ Urea Grade is a high-purity variant of ASTM 316L, specially developed for the urea industry. The grade has a guaranteed maximum ferrite content of 0.6%. Sandvik 3R60™ Urea Grade is characterized by:
- High resistance to corrosion in ammonium carbamate
- High resistance to intergranular corrosion
- Good weldability
- ASTM: TP316L
- UNS: S31603
- EN Number: 1.4435
- EN Name: X 2 CrNiMo 18-14-3
- W.Nr.: 1.4435
- DIN: X 2 CrNiMo 18 14 3
- SS: 2353
- BS: 316S13
Urea specifications issued by
ASTM A213, A312
Chemical composition (nominal) %
Forms of supply
Seamless tube and pipe- finishes and dimensions
Seamless tube and pipe in Sandvik 3R60™ Urea Grade is supplied in dimensions up to 260 mm outside diameter in the solution annealed and white pickled condition, or solution annealed by a bright annealing process.
U-tubes can be supplied on request.
Other forms of supply
- Urea high pressure pipe fittings and flanges
- Welding wire and filler wire/rods
- Covered electrodes
- Strip electrodes and flux for surfacing
Filler metals for welding
The sizes listed below are Sandvik stock standard. Local market stocks comprise sizes in common demand. For technical information on the filler metal please refer to brochures S-2361-ENG, S-2362-ENG and S-2366-ENG.
Welding wire and filler wire/rods
Sandvik 25.22.2.LMn: 1.20, 1.60 and 2.40 mm
Sandvik 25.22.2.LMnB: 2.5, 3.25 and 4.0 mm
Sandvik 25.22.2.LMn in 0.5 mm (0.02 in.) thickness. Widths by agreement.
For pipe with wall thicknesses greater than 10 mm (0.4 in.) the proof strength may fall short of the stated values by about 10 MPa (1.4 ksi). (1 N/mm2 = 1 MPa)
1 MPa = 1 N/mm2
a) Rp0.2 and Rp1.0 correspond to 0.2% offset and 1.0% offset yield strength, respectively.
b) Based on L0 = 5.65 √S0 where L0 is the original gauge length and S0 the original cross-section area.
The impact energy (Charpy V) at -60 °C (-75 °F) is minimum 150 J (110 ft-lb)
At high temperatures
|Temperature||Proof strength||Tensile strength|
|Temperature||Proof strength||Tensile strength|
Density: 8.0 g/cm3, 0.29 lb/in3
|Temperature, °C||W/m °C||Temperature, °F||Btu/ft h °F|
|Temperature, °C||J/kg °C||Temperature, °F||Btu/lb °F|
|Temperature, °C||Per °C||Temperature, °F||Per °F|
1) Mean values in temperature ranges (x10-6)
|Temperature, °C||MPa||Temperature, °F||ksi|
The low ferrite and impurity contents of Sandvik 3R60™ Urea Grade make it highly resistant to general and intergranular corrosion in the process solutions occurring in the manufacture of urea.
Sandvik 3R60™ Urea Grade easily meets the Huey test and selective attack requirements specified by Stamicarbon, Snamprogetti and Urea Casale. The general corrosion rate is normally set at 0.6 mm/year maximum for unsensitized material (24mpy, 3.3um/48h).
Tubes are delivered in the heat treated condition. If additional heat treatment is needed after further processing the following is recommended.
1050-1100°C (1920-2010°F), 5-20 minutes, rapid cooling in water.
Weldability of Sandvik 3R60™ Urea Grade is good. Suitable fusion welding methods are manual metal-arc welding with covered electrodes and gas-shielded arc welding, with the TIG and MIG methods as first choice. Preheating and post-weld heat treatment are not normally necessary. Since the material has low thermal conductivity and high thermal expansion, welding must be carried out with a low heat input and with welding plans well thought out in advance, so that the deformation of the welded joint can be kept under control. If, despite these precautions, it is foreseen that the residual stresses might impair the function of the weldment, we recommend that the entire structure is solution annealed. See under "Heat treatment".
The welded joint will be ferrite-free, which is essential for good resistance in corrosive urea solutions. To achieve maximum corrosion resistance, oxides and slag residuals must be removed from the weldment.
Recommended filler metals
Gas-shielded arc welding: Wire Sandvik 25.22.2.LMn.
Manual metal-arc welding: Covered electrodes Sandvik 25.22.2.LMnB.
Annealing after cold bending is not normally necessary, but the decision must be made after taking account of degree of bending and the operating conditions. Heat treatment, if any, should take the form of solution annealing, see under "Heat treatment". Hot bending is carried out at 1100–850°C (2010–1560°F) and should be followed by solution annealing.
The mechanical machining of stainless steels always requires an adjustment to cutting to data and machining method to give satisfactory results. When turning is undertaken with carbide tipped tools, the cutting speed should be reduced by 30% for finish machining and 60% for rough machining, compared with the cutting speeds applied for AISI 316. Much the same applies to other operations. If high speed steel tools are used, approximately the same cutting speed can be used as for AISI 316.
Detailed recommendations for the choice of tools and cutting data are provided in brochure S-1,462-ENG. Select data as for grade 5R60 (AISI 316), taking into account the above comments.
Typical urea plant applications of Sandvik 3R60™ Urea Grade are:
- Carbamate condensers
- High pressure piping.