Seamless Metallurgical Clad Pipe | Hot Extruded, Cold Finished & Pickled CRA Lined Tube for High Pressure Boiler & Heat Exchanger – Womic Steel

Q1: Why specify seamless clad pipe instead of welded clad pipe?
A: Seamless clad pipe has no longitudinal weld seam in either the core or the cladding. This eliminates a potential failure point under thermal fatigue, hydrogen service, or high pressure. It also avoids any risk of weld undercut or lack of fusion that could initiate corrosion. For boiler and heat exchanger tubes that must pass strict code requirements (ASME Section I, EN12952), seamless is often mandatory.

Q2: Can you provide the clad pipe with the CRA on the outside instead of the inside?
A: Yes. The extrusion process can be reversed: put the CRA on the OD and the carbon/alloy steel on the ID. Please specify at inquiry.

Q3: What is the bond strength of the cladding?
A: Typical measured shear strength from push-out tests is ≥300 MPa. This far exceeds requirements of API 5LD or any recognized standard. For extrusion-bonded clad tube, the interface is considered inseparable under normal service loads.

Q4: Do you perform the ultrasonic test to ASTM E213 or ISO 10893-10?
A: We are equipped to test to both standards. Typically we offer ISO 10893-10 for European-destined orders and ASTM E213 for ASME compliance. Please state your preference; we can also perform a combined test.

Q5: What about EN12952-2 part C – does your heat treatment and testing comply?
A: Yes. Our normalizing + tempering cycles are controlled and recorded as required by EN12952-2 C. The frequency of mechanical testing, flattening, and hydrostatic testing meets or exceeds the standard. We can provide a compliance matrix.

Q6: Is the pickling surface suitable for oxygen / hydrogen / clean steam service?
A: Pickling removes oxides but may leave traces of acid or moisture. For high-purity applications, we recommend additional degreasing and passivation (not included in standard pickling). Please specify this requirement.

Q7: How do I specify the exact dimensions for each combination?
A: Provide:

● Outer diameter (OD) of finished tube

● Core wall thickness (backing steel)

● Cladding thickness (CRA)

● Single length (e.g., 6m, 12m) and total length (m) per combination

Q8: Can you supply these clad tubes in U-bent configuration?
A: Yes, we can bend the finished pickled tube (cold bending with mandrel) followed by stress relief heat treatment and 100% NDT of the bent section. Please request a separate quote for U-bends.

Q9: What third-party inspection options exist?
A: We regularly work with SGS, BV, DNV, TÜV, ABS, and LR. The inspector can witness all or selected tests (hydro, UT, tensile, dimensional). We then issue EN 10204 Type 3.2 certificates.

Q10: Do you keep stock of these clad pipes?
A: We normally produce to order. However, standard items like SA-210+304L in popular diameters (e.g., 63.5×4.88×1.65mm, length 6m) may be available from a previous batch – please inquire.

Q11: What is the cost comparison vs. solid high alloy tube?
A: For the same pressure rating, a clad tube (e.g., T91+Alloy 28) typically costs 40-50% less than a solid Alloy 28 tube of equal OD and wall thickness. For SA-210+Incoloy 825, savings can be 50-60% compared to solid 825. The exact economy depends on cladding thickness and core material.

Q12: Do you have experience with VdTUV certification (e.g., for Incoloy 825 per VdTUV 432)?
A: Yes. We have supplied clad pipes to German plant operators requiring VdTUV approval. We can engage an authorized surveyor for VdTUV material acceptance and provide the required documentation.

Q13: How are the tube ends finished?
A: Standard: plain square cut, deburred. Optionally: beveled (30-35°), threaded (for mechanical couplings), or grooved. Beveled ends can be supplied with CRA buttering (a layer of matching alloy weld metal on the bevel face) to prevent dilution during field welding. Please specify.

Q14: What is the minimum cladding thickness for a reliable extrusion bond?
A: 1.5 mm is our safe minimum for seamless extruded clad pipe. For cladding thickness below 1.5 mm, the bond reliability decreases; we would recommend welded clad pipe instead. For most corrosion allowances, 2.02.5 mm is typical.

Q15: Is there a maximum length limit for seamless clad pipe?
A: Extrusion press capabilities limit single length to approximately 15 m for diameters under 100 mm. For larger diameters, the maximum length tends to shorter (12 m). If longer lengths are required (e.g., for reeling), we can examine the feasibility of cold-drawing longer pieces from extruded mother tubes.