Question 1

What is NACE MR0175 compliance for stainless steel pipe?

Accepted Answer

NACE MR0175/ISO 15156 is the international standard for materials used in H₂S-containing environments in oil and gas production. It specifies hardness limits (HRC ≤ 22 for austenitic stainless steels), chemical composition requirements, and heat treatment conditions to prevent sulfide stress cracking.

Question 2

What is the difference between 304L and 316L for sour service?

Accepted Answer

316L contains 2-3% molybdenum, providing superior pitting resistance in chloride-containing environments compared to 304L. For sour gas applications with both H₂S and chlorides, 316L is preferred. Both grades require carbon ≤ 0.03% for NACE compliance.

Question 3

What documentation is required for oil & gas pipeline projects?

Accepted Answer

Full material traceability is essential. TOKO TECH provides EN 10204 3.1 MTR (Material Test Reports), 100% PMI (Positive Material Identification) per tube, hydrostatic test reports, and NACE MR0175 compliance certificates for every shipment.

Question 4

Why use duplex 2205 instead of 316L for desalination?

Accepted Answer

2205 duplex stainless steel provides a PREN (Pitting Resistance Equivalent Number) of 35+ compared to 316L's PREN of ~25. This means 2205 can withstand chloride concentrations above 50,000 ppm at elevated temperatures where 316L would rapidly fail from pitting corrosion. Additionally, 2205's yield strength (450 MPa) is double that of 316L (170 MPa), allowing thinner wall pipe and reduced weight.

Question 5

What is PREN and why does it matter for desalination piping?

Accepted Answer

PREN = %Cr + 3.3 × %Mo + 16 × %N measures a stainless steel's resistance to pitting corrosion. For SWRO desalination plants operating with TDS above 50,000 ppm, a minimum PREN of 35 is recommended. 2205 achieves this through its balanced chromium (22%), molybdenum (3%), and nitrogen (0.15%) content.

Question 6

What standards apply to duplex pipe for desalination plants?

Accepted Answer

ASTM A790 governs seamless and welded duplex stainless steel pipe. NORSOK M-650 is often specified for offshore/desalination applications requiring additional qualification testing. ASTM A923 tests for the absence of detrimental intermetallic phases in duplex stainless steels.

Question 7

What is the difference between Alloy 800 and 800H?

Accepted Answer

Alloy 800H (UNS N08810) has a higher carbon content (0.05-0.10%) compared to standard Alloy 800 (≤ 0.10% but typically lower). The controlled higher carbon content, combined with Al+Ti additions (0.85-1.20%), promotes carbide strengthening at elevated temperatures, giving 800H superior creep rupture strength above 600°C compared to standard 800.

Question 8

What is carburization in ethylene cracking furnace tubes?

Accepted Answer

Carburization is the diffusion of carbon from the hydrocarbon process gas into the tube metal at high temperatures. This causes embrittlement, loss of ductility, and reduced thermal conductivity. Alloy 800H resists carburization through its protective chromium oxide scale (Cr₂O₃) that forms on the inner tube surface.

Projects & Case Studies

Natural Gas Long-Distance Pipeline — Compressor Station Piping

Mega-Scale SWRO Desalination Plant — Duplex 2205 Piping System

Ethylene Cracker Radiant Tubes — High-Temperature Alloy 800H & 304H

Agrochemical Reactor & Mixed-Acid Process Piping — 904L & Hastelloy C276

Ultra-Supercritical Thermal Power Plant — 321H & T91 Boiler Tubes

Refinery Hydrotreater Heat Exchanger Retube — 321 & 2205 U-Tubes

Hyperscale AI Data Center — 316L Liquid Cooling Piping System

LNG Terminal Cryogenic Piping — Southeast Asia

Pharmaceutical Sanitary Tubing — Europe

Titanium Heat Exchanger Seawater Cooling — Middle East