Views: 8 Author: Site Editor Publish Time: 2025-04-10 Origin: Site
Alloy steel buttweld fittings are wrought pipe fittings manufactured from alloy steels (carbon steel enhanced with elements like chromium, molybdenum, nickel, etc.), designed to connect, redirect, or modify the flow of pipe systems via butt welding.
A Buttweld pipe fitting is a type of pipe fitting that is designed to be joined to a piping system by welding the ends of the fitting to the ends of the pipes. The ends of buttweld fittings are typically beveled to allow for a full penetration weld, creating a strong and leak-proof connection.
How They Work:
End Preparation: The ends of buttweld fittings are machined with a bevel that matches the bevel on the end of the pipe. This bevel creates a groove when the fitting and pipe are aligned, which is then filled with weld material.
Welding: The fitting is then welded directly to the pipe, creating a permanent and continuous connection. Various welding techniques can be used, such as SMAW (stick), GTAW (TIG), GMAW (MIG), and SAW (submerged arc welding), depending on the material and application.
High strength & durability under pressure and temperature
Excellent resistance to thermal creep and corrosion
Smooth interior surface reduces turbulence
Suitable for critical service lines
Longer service life with correct material selection
Specifications | ASTM A234 / ASME SA234 |
Grades | WP1, WP5, WP9, WP11, WP22, WP91 |
Dimensions | ASME/ANSI B16.9, ASME B16.28, MSS-SP-43 |
Size | 1/8” NB TO 48” NB. |
Type | Seamless / Welded / Fabricated |
Thickness | Sch 5s, Sch 10s, Sch 40s, Sch 80s, Sch 160s, Sch XXS |
ASTM A234/A234M – 15
This specification covers wrought carbon steel and alloy steel fittings of seamless and welded construction covered by the latest revision of ASME B16.9, B16.11, MSS-SP-79, MSS-SP-83, MSS-SP-95, and MSS-SP-97. These fittings are for use in pressure piping and in pressure vessel fabrication for service at moderate and elevated temperatures. The M in the designation stands for metric.
CHEMICAL | LIMITS | C | Mn | P | S | Si | Cr | Mo |
ASTM A234 WP5 CL1,CL3 | MIN | 0.30 | 4.00 | 0.440 | ||||
MAX | 0.150 | 0.60 | 0.040 | 0.030 | 0.50 | 6.00 | 0.650 | |
ASTM A234 WP11 CL1 | MIN | 0.050 | 0.30 | 0.50 | 1.00 | 0.440 | ||
MAX | 0.150 | 0.60 | 0.030 | 0.030 | 1.00 | 1.50 | 0.660 | |
ASTM A234 WP11 CL2,CL3 | MIN | 0.050 | 0.30 | 0.50 | 1.00 | 0.440 | ||
MAX | 0.200 | 0.80 | 0.040 | 0.040 | 1.00 | 1.50 | 0.650 | |
ASTM A234 WP12 | MIN | 0.050 | 0.30 | 0.80 | 0.440 | |||
MAX | 0.200 | 0.80 | 0.045 | 0.045 | 0.60 | 1.25 | 0.650 | |
ASTM A234 WP22 CL1,CL3 | MIN | 0.050 | 0.30 | 1.90 | 0.870 | |||
MAX | 0.150 | 0.60 | 0.040 | 0.040 | 0.50 | 2.60 | 1.130 |
CHEMICAL | LIMITS | C | Mn | P | S | Si | Cr | Mo | V | N | Ni | Al | Nb | Ti | Zr | Sn | Sb | As | B | W |
TYPE 1 | MIN | 0.080 | 0.300 | 0.200 | 8.000 | 0.850 | 0.180 | 0.030 | 0.060 | |||||||||||
MAX | 0.120 | 0.600 | 0.020 | 0.010 | 0.500 | 9.500 | 1.050 | 0.250 | 0.070 | 0.400 | 0.020 | 0.100 | 0.010 | 0.010 | ||||||
TYPE 2 | MIN | 0.080 | 0.200 | 0.200 | 8.000 | 0.850 | 0.180 | 0.035 | 0.060 | |||||||||||
MAX | 0.120 | 0.400 | 0.020 | 0.005 | 0.400 | 9.500 | 1.050 | 0.250 | 0.070 | 0.200 | 0.020 | 0.100 | 0.010 | 0.010 | 0.010 | 0.003 | 0.010 | 0.001 | 0.050 |
MATERIAL | T.S (MPA) | Y.S (MPA) | EL % |
ASTM A234 WP5 CL1 | 415min | 205min | 30min |
ASTM A234 WP5 CL3 | 520min | 310min | 30min |
ASTM A234 WP11 CL1 | 415 min | 205 min | 30min |
ASTM A234 WP11 CL2 | 485min | 275min | 30min |
ASTM A234 WP11 CL3 | 520min | 310min | 30min |
ASTM A234 WP12 CL1 | 415 min | 220min | 30min |
ASTM A234 WP12 CL2 | 485 min | 275 min | 30min |
ASTM A234 WP22 CL1 | 415 min | 205 min | 30min |
ASTM A234 WP22 CL3 | 520min | 310min | 30min |
ASTM A234 WP91 | 620min | 415min | 20min |
It's not accurate to say that alloy steel is definitively "better" than stainless steel, or vice versa. They are both types of steel with different properties and are better suited for different applications. The "better" choice depends entirely on the specific needs and requirements of the application.
Alloy Steel:
Definition: Steel that has had other alloying elements (besides carbon) intentionally added to improve its mechanical and physical properties. Common alloying elements include manganese, silicon, nickel, chromium, molybdenum, vanadium, and others.
Stainless Steel:
Definition: A type of alloy steel that contains a minimum of 10.5% chromium by mass. This chromium content forms a passive, self-healing oxide layer on the surface, which is responsible for its excellent corrosion resistance.
Here's a table summarizing the key differences:
Feature | Alloy Steel | Stainless Steel |
Corrosion Resistance | Generally lower, can rust | Excellent due to high chromium content |
Strength/Hardness | Can be very high, tailored by alloying elements | Good, some grades can be very strong |
Cost | Generally less expensive | Generally more expensive |
Chromium Content | Varies, typically less than 10.5% | Minimum 10.5% |
Appearance | Varies | Often bright and shiny |
Primary Advantage | Tailorable mechanical properties (strength, etc.) | Superior corrosion resistance |
Typical Uses | Structural, high-strength components, tools | Corrosive environments, food/medical, aesthetic uses |
Conclusion:
Choose alloy steel when high strength, hardness, wear resistance, or specific mechanical properties are the primary requirements, and corrosion resistance is less critical or can be managed through coatings or other means. It's also often a more cost-effective option for such applications.
Choose stainless steel when corrosion resistance is paramount. Its ability to resist rust and degradation in various environments makes it essential for applications where hygiene, longevity in harsh conditions, and low maintenance are crucial, even if it comes at a higher initial cost.
All Fittings [Notes(1)and (2) | Center | Overall | Overall | 180 deg Returns | Lap Joint Ends | Angularity | ||||||||
Nominal | Outside | Inside | Center-to-Center | Back- | Align- | Outside | Fllet | Lap | Nominal | Off | Off | |||
1/2% to2 1/2 % | +0.06, | 0.03 | 0.06 | 0.06 | 0.12 | 0.25 | 0.25 | 0.03 | +0, | +0, | +0.06, | 1/2%to 4 | 0.03 | 0.06 |
3 to 3 1/2% | 0.06 | 0.06 | 0.06 | 0.06 | 0.12 | 0.25 | 0.25 | 0.03 | +0, | +0, | +0.06 | 5 to 8 | 0.06 | 0.12 |
4 | 0.06 | 0.06 | 0.06 | 0.06 | 0.12 | 0.25 | 0.25 | 0.03 | +0, | +0, | +0.06, | 10 to 12 | 0.09 | 0.19 |
5 to 8 | +0.09, | 0.06 | 0.06 | 0.06 | 0.25 | 0.25 | 0.25 | 0.03 | +0, | +0, | +0.06 | 14 to 16 | 0.09 | 0.25 |
10 to 18 | +0.16, | 0.12 | 0.09 | 0.09 | 0.25 | 0.38 | 0.25 | 0.06 | +0, | +0, | +0.12, | 18 to 24 | 0.12 | 0.38 |
20 to24 | +0.25, | 0.19 | 0.09 | 0.09 | 0.25 | 0.38 | 0.25 | 0.06 | +0, | +0, | +0.12, | 26 to 30 | 0.19 | 0.38 |
26 to 30 | +0.25, | 0.19 | 0.12 | 0.19 | 0.38 | 32 to 42 | 0.19 | 0.50 | ||||||
32 to 48 | +0.25, | 0.19 | 0.19 | 0.19 | 0.38 | 44 to 48 | 0.19 | 0.75 | ||||||
Feature | Socket Weld Fittings | Buttweld Fittings |
Connection Type | Pipe is inserted into a recessed socket, then welded around the outside | Pipe is butt-jointed end-to-end, then fully welded |
Welding Type | Fillet weld | Butt (groove) weld |
Pressure Rating | Suitable for small pipe diameters (typically up to 2" / DN50) and high-pressure systems | Used for larger pipe diameters, high-pressure and high-temperature applications |
Strength of Joint | Good, but not as strong as buttweld | Very strong, full penetration weld |
Appearance | Protruding weld and fitting | Smooth transition with beveled welds |
Installation Skill | Easier to install | Requires more skilled welding and fit-up |
Leak Potential | Slightly higher (crevice between pipe and socket) | Lower risk due to full weld and flush finish |
Cleanliness | Not ideal for hygienic or food-grade systems (crevice can trap material) | Preferred for hygienic applications (smooth interior) |
Code/Standard | ASME B16.11 | ASME B16.9 (or B16.28 for elbows/returns) |
✅ Summary:
Socket Weld = Simpler, smaller, quicker for small pipe sizes
Buttweld = Stronger, smoother, and preferred for critical & larger pipelines
1. Power Generation
High-pressure steam lines
Superheaters and reheaters
Boiler piping
Turbine piping systems
2. Oil & Gas Industry
Refinery piping
Hydrocracking and hydrotreating units
Offshore platforms and FPSOs
High-temperature oil transmission lines
3. Petrochemical & Chemical Plants
Reactor and heat exchanger piping
High-temperature corrosive fluid systems
Ammonia and urea production plants
4. Shipbuilding and Marine Engineering
Engine room high-pressure steam lines
Fuel and oil lines under high load
Requires fittings with high mechanical strength and corrosion resistance.
5. Industrial Piping Systems
Compressed air systems
High-temp gas transmission
Cryogenic applications (using low-temperature alloy grades)
-Pipe and Tube (EN 10216-5, ASTM A213, ASTM A249, A312, A790,)
-Forged Fitting and Flange (ASTM A182 , ASTM A105,ASTM B564 )
-Butt Weld Fittings (ASTM A234, ASTM A403,ASTM A815)
-Round bar , Billet (ASTM A276, ASTM A479)
- Plate, Sheet, Strip(ASTM A240, EN 10028-7, A480)
-Bolting, Nuts（ASTM A193, A194, A320）
We Export Alloy Steel Buttweld Pipe Fittings to Saudi Arabia, United Arab Emirates, Qatar, Bahrain, Oman, Kuwait, Turkey, Egypt, Yemen , Syria, Jordan, Cyprus, Singapore, Malaysia, Indonesia, Thailand, Vietnam, South Korea, Japan, Sri Lanka, Maldives, Bangladesh, Cambodia, Argentina, Bolivia, Brazil, Venezuela, Colombia, Ecuador, Guyana, Paraguay, Uruguay, United States Of America, Canada, Mexico, Panama, Jamaica, Bahamas, Denmark, Norway, Germany, France,Italy, United Kingdom, Spain, Belgium, Greece, Czech Republic, Portugal, Hungary, Albania, Austria, Finland, Ireland, Croatia, Malta, Nigeria, Algeria, Angola, South Africa, Libya, Egypt, Sudan, Europe, Africa, Asia, North America, South America, Middle East.etc
