Technical Blog — Page 2

Stainless, Duplex & Super Duplex (38)

• 6Mo Austenitic Stainless vs Duplex 2205 for Chloride Service: PRE, Strength, Fabricability, and Cost Trade-offs
  1 September 2026

  When 316L fails in chloride service, two upgrade paths are available: high-molybdenum austenitic stainless grades such as 254 SMO (EN 1.4547) or…

• Austenitic Stainless Steel Pipe Fittings in Cryogenic Service: LNG, Liquid Nitrogen, and Sub-Zero Impact Requirements
  1 September 2026

  Austenitic stainless steel pipe fittings — particularly 304L (UNS S30403, EN 1.4307) and 316L (UNS S31603, EN 1.4404) — are the standard materials for

• Austenitic Stainless Steel Work Hardening in Pipe Fitting Forming: Strain-Induced Martensite, Magnetic Response, and Annealing Recovery
  1 September 2026

  Austenitic stainless steel pipe fittings are manufactured by hot or cold forming — pressing, extrusion, or rolling — from flat plate or tubular blank…

• Caustic Stress Corrosion Cracking in Carbon, Alloy and Stainless Steel Pipe Fittings: NaOH Limits, PWHT and Grade Selection
  1 September 2026

  Caustic SCC in carbon, alloy and stainless steel fittings: NaOH concentration and temperature limits, weld stress, PWHT, and when to move to nickel alloys.

• Chloride Threshold for Stress Corrosion Cracking in Stainless Steel Pipe Fittings: Grade Comparison and Temperature Dependence
  1 September 2026

  Chloride stress corrosion cracking (Cl⁻ SCC) is one of the most consequential failure modes for austenitic stainless steel pipe fittings. The cracking is…

• Cobalt-Base Alloy Hard-Facing on Pipe Fittings: Stellite, Tribaloy, and When Erosion and Wear Resistance Requires More Than Stainless Steel
  1 September 2026

  Cobalt-base alloys — commercially known under the Stellite (Kennametal) and Tribaloy (Kennametal) trade names — are the highest-performance wear and…

• Corrosion Under Insulation on Carbon Steel and Stainless Steel Pipe Fittings: Risk Factors, Inspection, and Prevention
  1 September 2026

  Corrosion under insulation (CUI) is one of the most widespread and costly integrity threats in process plant — it has been identified as the single largest…

• Crevice Corrosion in Stainless Steel Pipe Fittings: Geometry, Critical Temperature, and Prevention
  1 September 2026

  Crevice corrosion is a localised corrosion attack that initiates within confined spaces — gasket faces, bolt holes, lap joints, socket weld annuli — where…

• Delta Ferrite in Austenitic Stainless Steel Weld Metal: Why It Is Required, How It Is Measured, and When It Becomes a Problem
  1 September 2026

  Delta ferrite (δ-ferrite) is a BCC iron-chromium phase that forms in austenitic stainless steel weld metal during solidification and is retained in the…

• Erosion-Corrosion in Multiphase Pipe Fittings: Flow Velocity, Sand Loading, and Material Selection
  1 September 2026

  Erosion-corrosion is the accelerated degradation of a pipe fitting caused by the combined action of mechanical erosion (from particle impact or…

• Ferritic Stainless Steel Pipe Fittings: 475°C Embrittlement, Sigma Phase, Grade Selection and Welding
  1 September 2026

  Ferritic stainless fittings (409/1.4512, 430, 444/1.4521): 475°C embrittlement, sigma phase, chloride SCC resistance, welding and switching from 316L.

• Galvanic Corrosion at Dissimilar Metal Pipe Fitting Joints: EMF Series, Area Ratio, and Insulation Kits
  1 September 2026

  Galvanic corrosion occurs when two dissimilar metals are in electrical contact in the presence of an electrolyte — the less noble (more anodic) metal…

• Grade 347H Stainless Steel Pipe Fittings: The Niobium-Stabilised Grade for High-Temperature Creep Service
  1 September 2026

  Both 347H (Nb-stabilised) and 321H (Ti-stabilised) resist sensitisation and provide high-temperature creep strength. The reason 347H is often…

• Intergranular Corrosion and Sensitisation in Stainless Steel Pipe Fittings: Cause, Testing, and Prevention
  1 September 2026

  Sensitisation is a microstructural change in austenitic stainless steel that renders it susceptible to intergranular corrosion (IGC) — preferential attack…

• Lean Duplex 2101 and 2304: The Cost-Saving Grades Between 316L and Duplex 2205
  1 September 2026

  The duplex stainless steel family is not limited to the well-known 2205 grade. Two leaner alloys — LDX 2101 (EN 1.4162, S32101) and 2304 (EN 1.4362…

• Nitrogen Purging and Preservation of Stainless Steel and Nickel Alloy Pipe Fittings During Storage and Transit
  1 September 2026

  Stainless steel and nickel alloy pipe fittings arrive at site with a passive surface that has been carefully maintained since final inspection. Inadequate…

• Non-Magnetic Pipe Fittings: When Magnetic Permeability Matters and How to Specify It
  1 September 2026

  Most pipe fitting engineers never need to think about magnetic permeability — but in a small number of specialist applications, ferromagnetism in…

• Pipe Fitting Packing and Preservation for Export: Moisture, Contamination, and End Cap Requirements
  1 September 2026

  Pipe fittings exported by sea freight spend weeks to months in transit and storage before installation, during which they are exposed to temperature…

• Pipe Fitting Storage and Preservation: How to Prevent Damage Before Installation
  1 September 2026

  Pipe fittings stored incorrectly between delivery and installation suffer corrosion, contamination, mechanical damage, and loss of traceability — defects…

• Pipe Fittings for Ammonia Service: Material Selection Across Refrigeration, Synthesis, and Handling
  1 September 2026

  Ammonia is one of the most widely produced industrial chemicals and one of the most treacherous for piping material selection. It is corrosive to copper…

• Pipe Fittings for Nitric Acid (HNO₃) Service: Why the Oxidising Environment Changes Everything
  1 September 2026

  Nitric acid service is one of the few environments where the grade selection logic for pipe fittings is the reverse of most acid services: highly…

• Pipe Fittings for Wet CO₂ and Carbon Capture Service: Corrosion Mechanism and Grade Selection
  1 September 2026

  Carbon capture and storage (CCS) projects, CO₂ injection for enhanced oil recovery (EOR), and wet CO₂ transportation pipelines share a common material

• Polythionic Acid SCC and Sulphur Service: Why Sensitised Stainless Steel Cracks During Shutdown
  1 September 2026

  Polythionic acid stress corrosion cracking (PTA-SCC) is a failure mechanism that is uniquely dangerous because it occurs not during normal plant operation…

• Sigma Phase Embrittlement in Duplex Stainless Steel Pipe Fittings: Formation, Detection, and Avoidance
  1 September 2026

  Duplex stainless steel pipe fittings — grades 2205 (UNS S31803/S32205) and super duplex 2507 (UNS S32750) — offer an excellent combination of strength…

• Thermal Shock and Quench Cracking in Austenitic Stainless Steel Pipe Fittings: Causes, Risk Zones, and Specification Controls
  1 September 2026

  Austenitic stainless steel pipe fittings are not immune to cracking during or after fabrication. Rapid temperature changes — from welding heat input…

• Weld Heat Input Calculation and Control for Duplex Stainless and CrMo Pipe Fittings
  1 September 2026

  Heat input is the energy delivered to the weld joint per unit length of weld — it determines the thermal cycle experienced by the base metal and HAZ, which…

• Pipe Fittings for Chlorine Dioxide Service: Material Selection in Pulp Bleaching and Water Treatment
  24 August 2026

  Chlorine dioxide (ClO₂) is one of the most demanding corrosive environments in industrial piping — more aggressive than chlorine in many…

• Pipe Fittings for Urea Synthesis: Material Selection in Carbamate and High-Pressure Streams
  16 August 2026

  Urea synthesis reactors operate at about 180–200°C and 140–200 bar with ammonium carbamate — one of the most corrosive chemical environments in the…

• 254 SMO vs Super Duplex 2507 in FGD Scrubbers: A Grade Selection Guide
  10 August 2026

  Flue Gas Desulphurisation (FGD) scrubbers present one of the most aggressive corrosion environments in power generation — hot dilute sulphuric acid…

• Pitting Corrosion and Critical Pitting Temperature: What PRE Doesn't Tell You
  5 August 2026

  PRE (Pitting Resistance Equivalent) is the single most cited metric for comparing stainless steel and duplex alloys in chloride-containing environments. It…

• Stress Corrosion Cracking in Pipe Fittings: Mechanisms, Thresholds, and Grade Selection
  28 July 2026

  Stress Corrosion Cracking (SCC) is one of the most insidious failure modes in process piping — the fitting looks intact under visual inspection, the…

• Duplex and Super Duplex Welding: Ferrite Control and Why It Matters
  24 July 2026

  Duplex and super duplex stainless steels derive their properties from a balanced 50/50 austenite-ferrite microstructure. Welding disrupts this balance…

• Thermal Expansion of Pipe Fittings: CTE by Grade and Its Impact on Piping Stress
  23 July 2026

  Every material expands when heated. In a piping system, unrestrained expansion causes displacement loads; restrained expansion causes thermal stress…

• 316L vs 316: Why Low Carbon Matters in Welded Pipe Fittings
  15 July 2026

  Most procurement specifications say "316 stainless steel fittings" without clarifying L or non-L. In a welded system, this distinction is critical.

• Duplex 2205 vs 316L: Which Grade for Your Application?
  15 July 2026

  Both grades are used in corrosive piping systems — but specifying 316L where 2205 is needed (or vice versa) leads to either premature failure or…

• Stainless Steel vs Carbon Steel Pipe Fittings: When to Upgrade
  14 July 2026

  When should carbon steel pipe fittings (A234 WPB, P265GH) be upgraded to stainless? Corrosion, temperature, low-temperature and purity criteria explained.

• 904L Pipe Fittings for Sulphuric Acid Service: Why This Grade Works
  11 July 2026

  Sulphuric acid (H₂SO₄) is one of the most widely used industrial chemicals — and one of the most corrosive to standard stainless steel. EN 1.4539…

• Super Duplex 2507 Pipe Fittings: The Offshore Seawater Standard
  10 July 2026

  When Duplex 2205 is insufficient for seawater at elevated temperatures or for the most aggressive chloride environments, Super Duplex 2507 (EN 1.4410) is…