Pipes & Tubes

API 5L is the American Petroleum Institute's specification for line pipe — designed for the transportation of oil, gas, and water from one location to another (gathering lines, transmission pipelines). It is available in both seamless and welded construction and comes in grades from Grade B through X80, at two quality levels (PSL1 and PSL2).

ASTM A106 is ASTM's specification for seamless carbon steel pipe for high-temperature service — designed for use within process plant boundaries (refineries, chemical plants, power stations) where the pipe carries process fluids at elevated temperatures. It is available in seamless construction only, in grades A, B, and C.

The key differences:

• API 5L = pipelines; ASTM A106 = plant process piping
• API 5L is available welded & seamless; A106 is seamless only
• API 5L has PSL1 and PSL2 quality levels; A106 has one quality level
• Design codes: API 5L → ASME B31.4/B31.8; A106 → ASME B31.3
• ASTM A106 specifies minimum silicon content (0.10%) for high-temp stability; API 5L PSL1 does not

PSL1 (Product Specification Level 1) is the basic quality level under API 5L — covering standard chemical composition, mechanical properties, and hydrostatic testing requirements.

PSL2 imposes significantly stricter requirements on top of PSL1, including:

• Mandatory Charpy V-notch impact testing (toughness verification)
• Stricter carbon equivalent (CE) limits for better weldability
• Maximum yield strength limits (prevents over-strength)
• Mandatory NDE of weld seams (welded pipe)
• More stringent dimensional tolerances
• Enhanced chemical composition control

When to specify PSL2: Sour gas service (H₂S present), offshore and subsea pipelines, sub-zero temperature service, fracture-critical pipeline segments, and any project where the operator's specification (ADNOC, Aramco, QatarEnergy, Shell, PDO, etc.) mandates PSL2. Most major oil company pipeline standards require PSL2 as a minimum.

Naftaar maintains ready stock of the following at our UAQ Free Trade Zone warehouse:

• ASTM A106 Grade B seamless — ½" to 12" NPS, all schedules (dispatch: 1-3 days)
• API 5L Grade B seamless — ½" to 12" NPS (dispatch: 1-3 days)
• API 5L Grade B ERW welded — 2" to 20" NPS (dispatch: 2-5 days)
• ASTM A53 Grade B ERW welded — ½" to 12" NPS (dispatch: 1-3 days)
• ASTM A312 TP304/TP316L seamless — ½" to 6" NPS (dispatch: 3-7 days)

For non-stocked grades (A335 alloy, A790 duplex, A333 low-temp, large-diameter LSAW), lead times are typically 6-12 weeks depending on grade, size, and mill availability. We confirm exact lead times with every quotation.

Yes. Naftaar can supply pipes that comply with NACE MR0175 / ISO 15156 for sour service (hydrogen sulphide / H₂S containing environments). Sour service compliance requires:

• API 5L PSL2 with carbon equivalent compliance for line pipe
• Restricted hardness limits (typically max. 22 HRC / 250 HBW)
• Controlled heat treatment (normalised or quenched & tempered)
• Charpy impact testing at specified temperature
• Supplementary SSC (Sulphide Stress Cracking) & HIC (Hydrogen Induced Cracking) testing where specified by the project
• Full documentation confirming NACE compliance

Please specify NACE MR0175 / ISO 15156 compliance in your RFQ, along with the partial pressure of H₂S and project service conditions, so we can confirm the appropriate material grade and test requirements.

Naftaar can supply pipes up to 120" NPS (3,048mm OD) in LSAW and HSAW/SSAW welded construction for API 5L line pipe. For seamless pipes, the practical maximum size available from most mills is 24" NPS (609.6mm OD) in carbon steel and stainless steel, and up to 36" NPS in some API 5L grades.

Large-diameter LSAW and DSAW pipes (16" to 120") are sourced back-to-back from approved mills — contact us with your project specifications for lead time and pricing confirmation.

Pipe wall thickness is determined by the design engineer based on the operating pressure, pipe material grade, design temperature, applicable design code, and safety factors. The basic calculation formula (from ASME B31.3) is:

t = (P × D) / (2 × (S × E + P × Y)) + A

Where: t = minimum required wall thickness (mm), P = internal design pressure (MPa), D = outside diameter (mm), S = allowable stress (MPa), E = quality factor, Y = yield factor, A = mechanical/corrosion allowance (mm)

Once the minimum wall thickness is determined, the next heavier schedule per ASME B36.10M (carbon/alloy steel) or ASME B36.19M (stainless steel) is selected. Naftaar's technical team can assist with schedule selection — contact us with your design parameters.

Naftaar does not impose a strict minimum order quantity. We supply both individual lengths and bulk project quantities. For stocked items, we can supply single pieces — though for very small quantities, freight costs may represent a significant proportion of the total cost. For mill-order items, minimum quantities are determined by mill minimum batch sizes, which typically range from 1 to 5 metric tonnes depending on grade and size. We advise on this in our quotation for each specific requirement.

Yes. Naftaar can supply duplex (UNS S31803 / S32205) and super duplex (UNS S32750 / S32760) stainless steel pipes for offshore and FPSO topside applications. For offshore service, pipe materials typically require:

• ASTM A790 compliance (seamless and welded duplex/super duplex)
• Class society approval (DNV-GL, Lloyd's Register, ABS, Bureau Veritas, ClassNK)
• NACE MR0175 compliance for sour service
• Ferrite content verification (typically 30-65% ferrite by FN number)
• Intermetallic phase testing (to detect sigma phase formation)
• Impact testing at specified temperature
• Third-party inspection and witness testing

Please provide your project specification, class society requirements, and service conditions in your RFQ for offshore duplex supply.