X65MS+Incoloy 825 Bimetal Metallurgical Clad Pipe | Sour Service CRA Lined Pipe for H₂S & CO₂ Environment – Womic Steel

Short Description:

Outer Pipe (Backing Steel): API 5L X65MS (PSL2) – sour service grade, low carbon, low sulfur, controlled hardness, SSC resistant

Inner Lining (CRA Cladding): Incoloy 825 (UNS N08825) – nickelironchromium alloy with molybdenum, copper, titanium; excellent resistance to H₂S, CO₂, chlorides, and reducing acids

Size Range: OD 219mm – 1016mm (8″ – 40″); Backing steel wall thickness 10mm – 30mm; Cladding thickness 2.0mm – 3.5mm; Single length up to 18m (custom 24m available)

Manufacturing Process: Hot roll bonding + JCOE forming – metallurgical bond interface shear strength ≥200 MPa; weld overlay on seam

Standards & Certifications: API SPEC 5LD (CRA Clad Steel Pipe), DNV-OSF101, NACE MR0175 / ISO 15156 (SSC/HIC compliant), ISO 13623. Mill Certificate EN 10204 Type 3.1/3.2. Thirdparty inspection (SGS, BV, DNV, TÜV, ABS, LR) available.

Applications: Wet sour gas pipelines, highH₂S gas gathering systems, acid gas injection wells (surface flowlines), Claus sulfur plant feed lines, highpressure CO₂−H₂S water disposal.

Womic Steel supplies X65MS+Incoloy 825 metallurgically bonded clad pipe – the proven solution for severe sour service. Backing steel meets NACE MR0175 hardness ≤248 HV; Incoloy 825 cladding resists SSC, HIC, and general H₂S/CO₂/Cl⁻ corrosion. Fully documented and thirdparty inspection ready.

Send email to us Product Specifications

Product Detail

Product Tags

1. Overview – Why X65MS+Incoloy 825 for Sour Service

Wet sour gas – containing hydrogen sulfide (H₂S), carbon dioxide (CO₂), and often chlorides – is one of the most aggressive environments for carbon steel pipelines. Standard X65 steel fails rapidly due to sulfide stress cracking (SSC) and hydrogen induced cracking (HIC).

X65MS+Incoloy 825 bimetal clad pipe is specifically designed for such conditions:

● Outer X65MS backing steel is a sour-service modified version of X65. It has low carbon (≤0.10%), low sulfur (≤0.002%), and controlled hardness (≤248 HV) to resist SSC and HIC as required by NACE MR0175 / ISO 15156.

● Inner Incoloy 825 cladding (UNS N08825) is a nickel-based alloy containing 38-46% Ni, 19-23% Cr, 2.5-3.5% Mo, plus copper and titanium. It withstands H₂S, CO₂, high chlorides, elemental sulfur, and organic acids across a wide pH and temperature range.

The two layers are permanently joined by a metallurgical bond (hot roll bonding + JCOE forming). Unlike mechanically lined pipe, there is no risk of liner collapse, wrinkling, or crevice corrosion at the interface.

This combination is the industry standard for onshore sour gas gathering, acid gas injection (AGI) flowlines, Claus plant feed lines, and high-pressure disposal wells.

2. Key Features & Benefits

Feature	Benefit
X65MS sour service backing	NACE MR0175 compliant – hardness ≤248 HV, SSC/HIC resistant
Incoloy 825 cladding	Resists H₂S, CO₂, chlorides, sulfur, organic acids – PREN 3035
Full metallurgical bond	No liner collapse / delamination – shear strength ≥200 MPa
Long service life	Typically 25-30 years in sour gas service
Cost savings	40-60% cheaper than solid Incoloy 825 or Alloy 625 pipe
Complete documentation	EN 10204 3.1/3.2; NACE compliance report; UT, MT, hydro test records

3. Technical Data & Material Specifications

3.1 Chemical Composition (%)

Element	X65MS Backing (max)	Incoloy 825 Cladding (typical)
Carbon (C)	0.10	≤0.05
Silicon (Si)	0.45	≤0.50
Manganese (Mn)	1.35	≤1.00
Phosphorus (P)	0.020	≤0.030
Sulfur (S)	0.002	≤0.015
Chromium (Cr)	0.30	19.5 – 23.5
Nickel (Ni)	0.30	38.0 – 46.0
Molybdenum (Mo)	0.15	2.5 – 3.5
Copper (Cu)	0.20	1.5 – 3.0
Titanium (Ti)	0.04	0.6 – 1.2
Vanadium (V)	0.08	—
Niobium (Nb)	0.05	—

3.2 Mechanical Properties

Property	X65MS Backing	Incoloy 825 Cladding
Yield Strength (min, MPa)	450	240 (annealed)
Tensile Strength (min, MPa)	535	550
Elongation (min, %)	18	30
Hardness (max, HV10)	248 per NACE	240
Impact (Charpy, 0°C, min J)	100 (avg)	—

3.3 Bond Interface & Corrosion Compliance

Parameter	Requirement	Notes
Shear strength	≥200 MPa	API 5LD
UT bond integrity	No disbond >50mm	100% scan
SSC resistance	Backing steel: NACE TM0177 Method A	No cracking at 80% SMYS
HIC resistance	Backing steel: NACE TM0284	CLR ≤15%, CTR ≤5%, CSR ≤2%
Incoloy 825 pitting	PREN = Cr+3.3Mo+16N ≈ 30-35	Resistant up to 150°C in high chlorides

3.4 Dimensional Range (Typical)

OD (inch/mm)	Backing WT (mm)	Cladding WT (mm)	Max Length (m)
8″ (219.1)	10.0 – 18.0	2.0 – 2.5	18
10″ (273.1)	10.0 – 20.0	2.0 – 2.5	18
12″ (323.9)	12.0 – 22.0	2.0 – 3.0	18
16″ (406.4)	12.0 – 25.0	2.5 – 3.0	18
20″ (508.0)	12.0 – 28.0	2.5 – 3.0	18
24″ (609.6)	14.0 – 30.0	2.5 – 3.0	18
30″ (762.0)	14.0 – 30.0	3.0 – 3.5	18
40″ (1016.0)	16.0 – 32.0	3.0 – 3.5	18

Custom sizes available on request.

4. Manufacturing Process – Hot Roll Bonding + JCOE

The manufacturing process for X65MS+Incoloy 825 clad pipe strictly follows sour service quality assurance:

● Material selection & verification – X65MS plate and Incoloy 825 plate are sourced from approved mills. OES chemistry and hardness are verified.

● Surface preparation – Both plates are cleaned and ground to remove scale and oxide.

● Vacuum stacking – Plates are stacked (Incoloy 825 inside), edges sealed under vacuum (≤10 Pa) to prevent oxidation during heating.

● Hot rolling – Stack heated to 1180-1250°C, rolled at high reduction ratio (≥5:1). Metallurgical bond forms by atomic diffusion.

● Clad plate inspection – 100% ultrasonic scanning for bond integrity.

● JCOE forming – Clad plate is edge-milled with stepped profile, then formed into open pipe via J-C-O presses.

● Longitudinal seam welding – Inner weld pass with Incoloy 625 filler; outer passes with low carbon steel filler. Welding procedure qualified to NACE/API 5LD.

● Weld cladding (optional overlay) – Inner weld seam may be overlaid with Incoloy 625 for enhanced corrosion resistance.

● Heat treatment – Stress relief (PWHT) if required by design code; otherwise no heat treatment to maintain backing steel sour service properties.

● NDT & testing – See Section 5.

● End finishing – Bevel ends + anti-rust oil + plastic caps.

5. Quality Control & Testing – Sour Service Focus

X65MS+Incoloy 825 clad pipe undergoes rigorous testing to ensure sour service integrity.

Test	Method / Standard	Scope	Acceptance
Chemistry & hardness (backing)	OES + HV10	Each heat	X65MS spec; hardness ≤248 HV
Hardness (cladding)	HV10	Each batch	≤240 HV
Bond UT	Full body, shear & longitudinal waves	100%	No disbond >50mm; total <2%
Weld seam UT	Automated phased array	100%	API 5LD / DNV F101
Weld MT / PT	Magnetic particle / dye penetrant	Weld start-stop, full length	No linear indications
Tensile & bend test	Transverse weld + bond shear	Per batch (≤50 pipes)	Failure outside weld / bond
Charpy impact (backing)	-20°C or -40°C	Per heat	≥100 J avg
SSC test (backing)	NACE TM0177 Method A (tensile)	Per heat / per project	No cracking at 80% SMYS
HIC test (backing)	NACE TM0284	Per heat / per project	CLR ≤15%, CTR ≤5%, CSR ≤2%
Hydrostatic test	1.5× design pressure	Each pipe	No leakage
Dimensional & visual	Laser / calipers / visual	100%	OD, WT, length, bevel

Additional tests on request:

● Pitting resistance (CPT / CCT) for Incoloy 825

● Intergranular corrosion (ASTM A262) for weld overlay

● Ferrite content (for weld metal)

6. Typical Applications & Project Experience

6.1 Onshore High-H₂S Gas Gathering

Location: Sichuan Basin, China (H₂S 8-15%, CO₂ 5-8%, chlorides moderate)
Pipe specification: X65MS+Incoloy 825, OD 323.9mm, backing WT 14.3mm, cladding 2.5mm
Service life goal: 30 years. Supplied 47 km to major NOC. In service since 2019 – zero corrosionrelated failures.

6.2 Acid Gas Injection (AGI) Flowline

Location: Middle East offshore (H₂S + CO₂ + high chlorides)
Challenge: Condensed water phase extremely corrosive.
Solution: X65MS+Incoloy 825 clad pipe, OD 406.4mm, cladding 3.0mm.
Outcome: Installed as topside-to-wellhead flowline; passed NACE TM0177 and TM0284 qualification.

6.3 Claus Plant Feed Line (Elemental Sulfur Service)

Location: Gulf Coast, USA refinery
Problem: Liquid sulfur + trace HCl caused rapid attack on carbon steel.
Solution: X65MS+Incoloy 825 clad pipe (12″ OD, 2.8mm cladding).
Result: 8 years in service without any liner or backing steel degradation.

7. Why Choose Womic Steel for Sour Service Clad Pipe?

Reason	Details
Specialized in sour materials	Extensive experience sourcing lowhardness X65MS plate and Incoloy 825
In-house NACE expertise	Technical team can prepare full NACE compliance dossiers
Full traceability	From heat numbers of both layers to final hydro test
Short lead time	12-16 weeks for standard sizes (repeat orders 10-12 weeks)
Global third-party approval	Work with DNV, BV, TÜV, SGS for witness inspection and 3.2 certificates
Competitive pricing	40-60% less than solid Alloy 825 or Inconel 625 pipe

8. Frequently Asked Questions (FAQ)

Q1: What is the difference between X65 and X65MS?
A: X65MS is a “sour service” modification of X65. It has lower carbon (≤0.10%), very low sulfur (≤0.002%), tighter hardness control (≤248 HV), and mandatory SSC/HIC testing per NACE MR0175. Standard X65 is not suitable for wet H₂S.

Q2: Why use Incoloy 825 instead of 316L or duplex for sour service?
A: Incoloy 825 contains high nickel (38-46%), which provides excellent resistance to chloride-induced SCC and SSC. It also resists reducing acids (e.g., HCl) and elemental sulfur – conditions where 316L and duplex will fail. For very severe sour service (high H₂S + high chlorides + elemental S), Incoloy 825 is often the minimum acceptable CRA.

Q3: Can Incoloy 825 cladding be welded to itself or to carbon steel?
A: Yes. Incoloy 825 is weldable by GTAW (TIG), GMAW (MIG), and SMAW. For joining cladding to cladding, use filler metal Alloy 82 / 82i (ERNiCr-3) or Alloy 625 (ERNiCrMo-3). For joining cladding to carbon steel (e.g., weld overlay), use an intermediate layer of Alloy 309L or 625 to avoid dilution and cracking.

Q4: Is the longitudinal seam weld also sour service resistant?
A: Yes. The inner pass is welded with Incoloy 625 filler (higher Ni, Cr, Mo than 825). This weld overlay provides equal or better corrosion resistance than the 825 cladding. The entire weld is 100% NDT inspected and hardness tested.

Q5: What certifications are provided for sour service?
A: We issue EN 10204 Type 3.1/3.2 certificates that include backing steel heat analysis, hardness, SSC and HIC test reports (if performed), and weld hardness survey. Upon request, we provide a NACE MR0175 compliance letter.

Q6: What is the typical lead time for X65MS+Incoloy 825 clad pipe?
A: First order: 14-18 weeks (includes sour service material procurement and qualification). Repeat orders: 10-12 weeks. Third-party inspection may add 1-2 weeks.

Q7: Can Womic Steel supply Inconel 625 clad pipe instead of Incoloy 825?
A: Yes. For even more severe conditions (high temperature, high H₂S, high chlorides), we offer X65MS+Inconel 625 (UNS N06625) clad pipe. Inconel 625 has higher strength and better pitting resistance (PREN >45). Contact us for a separate datasheet.