Steel Material Selection Guide for Petrochemical Plants

The Importance of Material Selection in the Petrochemical Industry

In petrochemical and refinery plants, material selection is a critical engineering decision for plant safety and economic service life. Factors such as high temperature, high pressure, corrosive environments, and hydrogen effects make correct steel grade determination mandatory. Incorrect material selection can lead to unplanned shutdowns, safety risks, and significant financial losses.

Step 1: Determining Operating Conditions

The first step in material selection is clearly defining the conditions the equipment will be exposed to:

Temperature Assessment

• Ambient temperature - 200°C: Carbon steels (A105, A350 LF2) are sufficient
• 200°C - 450°C: Chromium-molybdenum steels (A182 F11, F22)
• 450°C - 600°C: High chromium alloys (A182 F91, F92)
• Above 600°C: Austenitic stainless or nickel alloys

Pressure Assessment

ASME B16.5 pressure classes (Class 150 - 2500) must be evaluated together with temperature. Remember that the allowable pressure decreases at elevated temperatures.

For pressure class calculations, you can use our Pressure Class Tool page.

Step 2: Corrosion Mechanism Analysis

Common Corrosion Types

• Sulfidation: In H2S-containing environments, accelerates above 260°C
• Naphthenic acid corrosion: In crude oils with high TAN values
• High Temperature Hydrogen Attack (HTHA): Nelson curves are referenced in high-pressure hydrogen environments
• Chloride stress corrosion cracking: Critical risk in austenitic stainless steels
• CO2 corrosion: Carbon steel degradation in wet CO2 environments

Material-Corrosion Matching

Corrosion Type	Recommended Material
General atmospheric	A105, A350 LF2
Sulfidic (moderate)	A182 F5, F9
Sulfidic (severe)	A182 F22, 316SS
Hydrogen service	A182 F22 (with PWHT)
Naphthenic acid	316Ti, 317L

Step 3: Standard and Specification Selection

Main material standards used in petrochemical plants:

• ASTM A105: Carbon steel forged flanges and fittings
• ASTM A182: Alloy and stainless steel forged parts
• ASTM A350: Low-temperature carbon steel forged parts
• ASTM A694: High-strength forged fittings

Step 4: Additional Requirements

Impact Testing

• Charpy impact test is mandatory when minimum design temperature is below -29°C
• A350 LF2: Guaranteed impact values down to -46°C

NACE MR0175 / ISO 15156 Compliance

In sour service environments:

• Hardness limit: max. 22 HRC (carbon and low-alloy steels)
• Mandatory PWHT (post-weld heat treatment)
• Special production procedures and certification

Heat Treatment Requirements

• Normalization: Homogenization of grain structure
• Normalization + Tempering: Improvement of mechanical properties
• PWHT: Relief of weld residual stresses

Step 5: Flange and Fitting Dimensioning

After correct material selection, you can use our Flange Dimensions Tool page to determine flange dimensions. You can access detailed dimension information by NPS, pressure class, and flange type.

Aktif Çelik Petrochemical Solutions

As Aktif Çelik, we supply forged flanges, fittings, and bar stock in ASTM A105, A182 (F11, F22, F304, F316), and A350 LF2 grades for the petrochemical industry. With our 3.1 certified, NACE-compliant products and technical engineering support, we are your reliable solution partner for your projects. Contact our team for customized material selection consultancy for your plant requirements.