ASTM A105 Pipe Elbow – Forged Carbon Steel Elbows

What You Need to Know Before Buying A105 Elbows

If you're buying small-bore, high-pressure elbows for instrument lines, hydraulic systems, or wellhead piping, you've probably come across ASTM A105 forged elbows. A105 is the standard for forged carbon steel piping components, and it's the go-to material for socket-weld and threaded elbows in sizes from NPS 1/8″ to 4″.

This guide covers the four main decisions you'll need to make: pressure class, connection type, heat treatment, and material certification.

What is an A105 Forged Elbow?

ASTM A105 forged elbows are produced in accordance with ASME B16.11. Unlike A234 WPB butt-weld elbows formed from pipe, A105 elbows are hot forged from solid steel billets. This forging process delivers dense, uniform microstructure, making them ideal for high-pressure small-bore applications.

Applicable service temperature ranges from -29°C to 425°C. For sub-zero or sour service, normalized A105N with NACE MR0175 certification is required.

Where A105 Forged Elbows Are Used

A105 elbows are common in:
● Instrument lines — small-bore, high-pressure tubing connections
● Hydraulic systems — where Class 3000 or 6000 fittings are required
● Wellhead piping — surface connections on oil and gas wells
● Utility stations — steam, water, and air lines in process plants

They are not typically used for large-diameter main process piping, where butt-weld elbows (A234 WPB) are more economical.

A105 vs. A234 WPB: Which One for Your Elbow?

This is one of the most common questions buyers ask. ASTM A105 and A234 WPB elbows are both made of carbon steel, but they're used for different fitting types.

Parameter	ASTM A105	ASTM A234 WPB
Manufacturing	Forged	Wrought (formed from pipe)
Standard	ASME B16.11	ASME B16.9
Connection	Socket weld / Threaded	Butt weld
Typical size	NPS 1/8″ – 4″	NPS 1/2″ – 48″
Pressure basis	Fixed class (3000# / 6000#)	Pipe schedule (Sch 80, Sch 160)
Typical use	Small-bore high-pressure, instrument lines	Main process piping, large diameter
Tensile strength	≥ 485 MPa	≥ 415 MPa
Relative cost	Higher per unit	Lower for large quantity

Rule of thumb: 

Small diameter (NPS ≤ 2), socket weld or threaded connection → A105
Large diameter (NPS ≥ 2), butt weld → A234 WPB

Common mistake: Using A105 for butt weld fittings and A234 WPB for socket weld fittings. Materials should match the connection type and size range.

Pressure Class: Class 3000 or Class 6000?

A105 forged elbows come in two pressure classes under ASME B16.11: Class 3000 (3,000 psi, matches Sch 80 pipe) and Class 6000 (6,000 psi, matches Sch 160 pipe). Which one you need depends on your design pressure and pipe schedule.

One rule you can't skip: 

The fitting bore has to match the pipe bore. If you put a Class 6000 elbow on Sch 80 pipe, you'll create a step at the connection. That causes turbulence and can lead to fatigue cracking.

▶ For a full comparison of pressure ratings, body dimensions, and selection rules, see our guide: [Class 3000 vs. Class 6000 Socket Weld Fittings] .

Connection Type: Socket Weld or Threaded

Connection Type	Pressure Suitability	Key Characteristic	Typical Application
Socket Weld	Class 3000–9000	Permanent connection; fillet welded; better fatigue resistance	High-pressure process piping, hydraulic systems
Threaded (NPT)	Class 2000–6000	Can be taken apart; needs thread sealant	Instrumentation, utility lines, low-vibration services

Note: Socket-weld elbows are more commonly used for high-pressure and critical service conditions, whereas threaded elbows are suitable for applications requiring pipeline disassembly but are not appropriate for environments involving vibration or high-temperature cycling.

Size Range and Availability

Class 3000 elbows are widely stocked from NPS 1/8″ to 4″. Class 6000 is usually limited to NPS 2″ and below. For sizes above 2″, Class 3000 is the standard choice. If you need a larger size in a high-pressure class, look at a seamless elbow with butt-weld ends instead.

Heat Treatment: A105 or A105N?

A105 and A105N have the same chemical composition and mechanical properties. The only difference is heat treatment.

Standard A105 comes in the as-forged condition. Heat treatment isn't mandatory for all sizes, though it's generally recommended. A105N is normalized — the "N" means the forging has been normalized to refine the grain structure and improve toughness.

When to specify A105N:
● Service temperatures below -29°C
● High-pressure classes (Class 300 and above)
● NACE MR0175 (sour service) applications
● Projects that require low-temperature impact testing

Note: If your project calls for NACE MR0175 or low-temperature impact testing, go with A105N. Many end users won't accept the A105 heat treatment exception for critical services.

Material Certification: Documents to Request from Suppliers

When ordering A105 forged elbows, please request the following documents:

1. MTR (Material Test Report) – showing chemical composition and mechanical properties
2. Heat Treatment Report – confirming normalization or annealing (for A105N grade)
3. NDT Report – results of ultrasonic, magnetic particle, or liquid penetrant testing
4. NACE MR0175 Certificate – applicable for sour service conditions

Note: Always verify whether the MTR was issued by the original manufacturer or a third-party laboratory. For critical applications, MTRs issued by the original manufacturer are preferred.

Order Checklist

Here's a quick checklist to run through before placing your order:

□ Pressure class (3000# or 6000#) matches pipe schedule
□ Connection type (socket weld or threaded)
□ Heat treatment condition (A105 or A105N)
□ Size (NPS and quantity)
□ MTR required? Original mill or third-party?
□ NACE MR0175 certification required?
□ NDT requirements (UT, MT, PT)

FAQ for Buyers

Q1: What's the typical lead time for A105 socket weld elbows?
A: Class 3000 elbows in common sizes (NPS 1/2″ to 2″) are usually stocked and ship in 1–2 weeks. Class 6000 and non-standard sizes may take 3–4 weeks. Always confirm with your supplier before placing a firm order.

Q2: What's the minimum order quantity?
A: It depends on size and pressure class. For standard Class 3000 sizes, we can handle small quantities. For Class 6000 or special sizes, a minimum order may apply.

Q3: Can A105 elbows be used in sour service?
A: Only if they meet NACE MR0175 requirements. Standard A105 may not meet the hardness (≤ 187 HB) and sulfur content (S ≤ 0.02%) limits. Specify A105N with NACE certification for sour service.

Q4: Do you provide test certificates with the shipment?
A: Yes. Every shipment includes the MTR, heat treatment report (if applicable), and NDT report (if specified). We can also send certificates in advance for your review.

△ Need A105 Elbows for Your Project?

We supply A105 forged elbows in Class 3000 and Class 6000, socket weld and threaded connections, sizes NPS 1/8″ to 4″. A105N and NACE MR0175 certified material available on request.

▶ [Request a quote or send us your specifications]

Related Resources

●  SCH 40 Pipe Elbow

●  ASTM A234 WPB Elbow

●  ASTM A105 Carbon Steel Forgings Specification

●  Class 3000 vs. Class 6000 LB Forged Fittings Pressure Rating