Quick calculators for weldability, corrosion resistance and welding — each with its formula, units and valid range. For guidance only: they do not replace a qualified engineer or the governing code.
Every result on this page is for guidance only. The calculators screen a chemistry or a welding setting against the usual rules of thumb; they do not replace a welding procedure qualification, a corrosion study, NACE MR0175 / ISO 15156 or the judgement of a qualified engineer.
How readily a carbon or carbon-manganese steel hardens next to a weld, from its chemistry. The higher it is, the more preheat the weld needs to avoid hydrogen cracking.
CE = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15, elements in mass %.
Bands: up to 0.40 usually welds without preheat; 0.41–0.50 may need preheat; above 0.50 needs preheat and a qualified procedure. Thickness, hydrogen level and restraint move these lines.
The carbon equivalent used for modern low-carbon, micro-alloyed steels such as line pipe, where the IIW formula overstates the effect of manganese.
Pcm = C + Si/30 + (Mn + Cu + Cr)/20 + Ni/60 + Mo/15 + V/10 + 5B
Line pipe specifications such as API 5L PSL 2 commonly cap Pcm at 0.25 when carbon is 0.12% or less.
The pitting resistance equivalent number ranks stainless steels by their resistance to pitting and crevice corrosion in chloride, from the elements that matter most: chromium, molybdenum and nitrogen.
With tungsten (PRENW):
PREN = Cr + 3.3 Mo + 16 N; with tungsten, PRENW = Cr + 3.3 (Mo + 0.5 W) + 16 N.
Typical values: 304 ≈ 19, 316L ≈ 25, 2205 duplex ≈ 35, 2507 super duplex ≈ 43. Projects in seawater often ask for 40 or more.
For nickel-base corrosion-resistant alloys (825, 625, C-276 and similar) a form that also counts tungsten and niobium is in common use.
PREN = Cr + 1.5 (Mo + W + Nb)
The average general corrosion rate of a coupon from the mass it lost in a test.
CR = 87.6 × W ÷ (D × A × T) mm/y — W in mg, D in g/cm³, A in cm², T in hours. 1 mm/y = 39.37 mpy.
The extra wall to add for the metal expected to corrode away over the design life.
CA = rate × design life. With an inhibitor: rate = f × inhibited + (1 − f) × uninhibited, f = availability.
The energy put into the joint per millimetre of weld. It sets the cooling rate, and with it the toughness and hardness of the weld and the heat-affected zone.
HI = (V × I × 60) ÷ (1000 × S) × k kJ/mm, S in mm/min, k the thermal efficiency of EN 1011-1.
Carbon and low-alloy steels in wet H₂S service are usually held to a maximum hardness, most often quoted as 22 HRC (about 248 HV or 237 HB), to resist sulfide stress cracking.
This is a hardness screen only — not a check of compliance with NACE MR0175 / ISO 15156, which also sets chemistry, heat treatment, weld and environment limits.
Limit used: 22 HRC ≈ 248 HV ≈ 237 HB (approximate conversions — see the hardness converter).
The calculators are given as a service. MESteel accepts no liability for their results or for any use made of them.
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