This is the question we hear most often when a flange is ordered: A105 or A182? They are not two materials but two standard families.
The basic difference
- ASTM A105 covers carbon steel forged parts for pressure systems. There is a single grade.
- ASTM A182 covers alloy and stainless forged parts and contains many grades: F304/F304L, F316/F316L (stainless), F11, F22, F91 (chromium molybdenum), F51, F53 (duplex and super duplex), F44 (super austenitic).
So "A182" alone is not a material name; the grade must always be written with it.
Which goes where
| Service | Suitable grade |
|---|---|
| General process, water, steam, hydrocarbons (ambient – 400 °C) | A105 |
| Low temperature (below −29 °C) | A350 LF2 |
| High temperature (450 – 600 °C) | A182 F11, F22, F91 |
| Corrosive, chloride bearing, food and pharma | A182 F304L, F316L |
| High chloride, geothermal brine, sea water | A182 F51, F53 |
| Sour service (H2S) | NACE compliant A105 or a suitable A182 grade |
Cost and lead time
A105 is both the most economical and the easiest to find in stock. On the A182 side, F304L and F316L are common stock items, while F11, F22, F91 and duplex grades usually come from production with longer lead times. Early ordering matters when a project includes alloy items.
Ordering notes
- Writing "A182" is not enough; state the grade, such as F316L
- Dual grade marking (F316/F316L) is generally accepted, but check the specification
- Request PMI reports and heat treatment records for alloy items
- Ask for hardness values on the certificate in sour service
See what is an ASTM A105 flange and stainless flange selection, and send your list through the enquiry form.
FAQ
Is A182 a material name?
No, it is a standard containing many grades. The grade must be stated on the order.
Can F316 replace A105?
It can, for corrosion reasons, but cost and strength differ; follow what the piping class list specifies.
Why are alloy grades slow to deliver?
F11, F22, F91 and duplex grades are usually made to order rather than held in stock.
Send us your material list; we reply with price and lead time the same day.
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