Forged vs Seamless Pipes Compared

Quick Reference

Forged pipes are ID-controlled (minimum wall thickness guaranteed), preferred for: large OD (>18”), heavy WT (>40mm), small lots, tight tolerances (nuclear, offshore). Seamless pipes are OD-controlled (average wall thickness), preferred for: standard sizes (1/2”-18”), normal WT, large quantities. Learn more about seamless/welded pipe types.

Forged vs seamless pipe design comparison

Forged Vs. Seamless Pipe

What Is a Forged Pipe?

Definition

A forged pipe is manufactured by forging, a process that shapes metals through localized compressive forces. The term “forged” refers to the manufacturing method, not to the shape or application of the pipe.

forged pipe The forging process involves heating a metal piece, then hammering or pressing it into the desired shape. For pipes, the process starts with a cylindrical billet that is pierced to create a hollow center, similar to the initial steps of seamless pipe manufacturing. The difference is in the subsequent steps, where the metal is mechanically worked (CNC machined) to achieve the final dimensions and properties.

Manufacturing Process of Forged Pipes

The main production steps for forged seamless pipes are depicted below:

manufacturing process forged pipe

Step	Process	Purpose
1	Billet Preparation	Produce solid cylindrical billets cut to desired length
2	Billet Heating	Heat billets to reduce yield strength and enable plastic deformation
3	Forging	Apply compressive forces to shape billets into cylindrical pipe forms
4	Piercing	Create hollow tube with uniform inner diameter
5	Rolling and Sizing	Elongate and reduce diameter to achieve desired dimensions and wall thickness
6	Heat Treatment	Relieve stresses, refine grain structure, enhance mechanical properties
7	Machining	Achieve final dimensions, surface finish, and tolerances
8	Testing and Inspection	Verify quality and conformance to specifications
9	Finishing and Packaging	Clean, finish, and package for shipping

Billet Preparation

The process begins with solid cylindrical billets of steel or other suitable materials, typically produced by continuous casting or hot rolling, and cut to the required length.

Billet’s Heating

The billets are heated to high temperatures in a controlled atmosphere furnace to increase malleability. Heating reduces the material’s yield strength and allows plastic deformation during forging.

Forging

The heated billets are placed under a forging hammer or press and deformed into cylindrical shapes through compressive forces. Forging may be performed in multiple stages to reach the target dimensions and mechanical properties.

Piercing

After forging, the rough blanks are pierced to create a hollow tube with a uniform inner diameter. The blanks are forced through dies and rollers to remove excess material and form the inner surface.

Rolling and Sizing

The pierced blanks are elongated and reduced in diameter through a series of rolling passes until the target dimensions and wall thickness are reached. Hot or cold rolling may be used depending on the material and specifications.

Heat Treatment

Once formed and sized, the pipes undergo heat treatment (annealing or tempering) to improve mechanical properties and microstructure. Heat treatment relieves internal stresses, refines grain structure, and improves strength, toughness, and ductility.

Machining

After heat treatment, the pipes undergo machining operations (turning, boring, threading) to reach final dimensions, surface finish, and tolerances. Machining removes surface defects and ensures dimensional accuracy.

Testing and Inspection

Throughout production, forged pipes are tested and inspected for quality and specification conformance. Non-destructive methods include ultrasonic testing, eddy current testing, and visual inspection; destructive methods include tensile testing and hydrostatic testing.

Finishing and Packaging

After passing all quality checks, the pipes are finished, cleaned, and packaged for shipment.

In summary, forged pipe production combines forging and machining techniques to produce seamless pipes with controlled mechanical properties and tight dimensional tolerances.

The picture below represents a forging press of approximately 12.000 tons:

Industrial forging press (approx. 50,000 tons capacity)

Features of Forged Pipes

Feature	Description
Enhanced Strength	Forging refines the grain structure and aligns it to the pipe shape, producing uniform composition and superior strength and fatigue resistance compared to cast or machined parts.
High Durability	No seams means no weak points. Forged pipes withstand extreme internal pressures and harsh environmental conditions.
Customizability	Forged pipes can be tailored to specific sizes and shapes, with more flexibility than casting or extrusion.
Superior Reliability	The homogenous structure reduces the risk of hidden defects (voids, inclusions) that can cause failure under stress.
Chemical Resistance	The absence of seams and uniform structure improve chemical resistance, as there are no preferential corrosion paths.
Thermal Stability	Forged pipes maintain structural integrity across a wide temperature range, making them suitable for high-temperature service.
Corrosion Resistance	Without welds or seams that are prone to preferential attack, forged pipes perform better in corrosive environments than welded alternatives.

Elective Applications of Forged Pipes

Application	Why Forged Pipes Are Preferred
High-Pressure Applications	Systems operating under high internal pressures, such as hydraulic circuits.
Oil and Gas Industry	Drilling and transport lines requiring high strength and pressure resistance.
Power Generation	Steam lines and other high-consequence piping within power plants.
Chemical Processing	Process piping exposed to corrosive substances and elevated temperatures.
Marine Applications	Offshore piping requiring both strength and corrosion resistance in seawater exposure.
Nuclear Industry	Nuclear plant piping where reliability and strict tolerance control are mandatory.

What Is a Seamless Pipe?

A seamless pipe has no welded joints or seams. It is produced by drawing a solid billet over a piercing rod to create a hollow shell.

Piercing mill seamless pipes

The production process of seamless pipes is fully automated and mainly oriented to standard sizes and large quantities (an order could go from a minimum quantity of 20 pipes to a pipeline order with 5.000 km / 450 pipes of the same size). Pipes are not mechanically CNC machined except for the ends (pipe ends are beveled or threaded to allow connection of each pipe).

The manufacturing process of a seamless pipe can be outlined as follows:

Step	Process	Description
1	Heating of the Billet	A solid round steel billet is heated at a high temperature to make it pliable.
2	Piercing	Once the billet is heated enough, it is pierced through the center using a piercer to create a hollow shell. This is often done on a rotary piercing mill where the billet is fed between rollers and a mandrel (piercing rod) to start the hollowing process.
3	Rolling	The hollow shell is then elongated and rolled to give it the desired thickness and diameter. This is usually achieved using a series of rolling mills, which may include a mandrel mill and plug mill. In the mandrel mill, a mandrel bar is inserted into the tube and the assembly is then rolled until the desired dimensions are achieved.
4	Sizing	After rolling, the tube may be further processed to achieve the precise size and tolerances required. This can include additional passes through a reducer mill and sizing mill.
5	Heat Treatment	To achieve the desired mechanical properties, the pipe is then subjected to heat treatment such as annealing or quenching and tempering.
6	Finishing	Finally, the pipe undergoes finishing steps, which may include cutting, straightening, inspecting, and sometimes further machining.

Learn more about seamless pipes and their manufacturing process.

Seamless pipes are used where strength under extreme pressure is required: oil and gas, chemical plants, power generation, and machinery components. They handle greater stress than welded pipes, which have a seam that can be a weak point under pressure and temperature cycling.

Differences Between Forged and Seamless Pipes

Summary

The fundamental difference: forged pipes are ID-controlled (minimum wall thickness guaranteed), while seamless pipes are OD-controlled (average wall thickness, with tolerances up to -12.5%). This distinction directly impacts pressure calculations, welding fit-up, and installation costs.

Dimensional Parameters

Parameter	Forged Pipe	Seamless Pipe
Defined by	Outside Diameter (OD) + Inside Diameter (ID)	Outside Diameter (OD) + Wall Thickness (WT)
Control type	ID-controlled	OD-controlled
Also known as	”Minimum Wall Thickness Pipes” (minimum thickness guaranteed)	“Average Wall Thickness Pipes”

Forged vs seamless pipe dimensions Seamless pipes are also called “OD-controlled pipes” or “Average Wall Thickness Pipes”. The theoretical size of each pipe is different from the actual one (due to limitations in production, and the international norms allowing some dimensional tolerances). For example, in an OD-controlled size OD711 mm x WT 50 mm, the actual ID might show a 25 mm difference from the ordered (= theoretical) one.

This size difference (actual vs. theoretical) might generate unexpected costs and delays during installation at the site. The welding of two pipes with different IDs might require longer time or extra machining of pipe ends (that were not accounted for during the pipework engineering process).

Imperfect welding might be very critical in offshore applications or for pipes installed within a power plant, as high-temperature steam might generate unwanted vortex movements, cavitation, and creep problems to all the ancillary utilities existing in the plant.

Cost-Effectiveness

Theoretically, a forged pipe could be produced in any desired size. The question is: when is it better to go for a forged vs. a seamless pipe?

In general, forged pipes are more cost-efficient, compared to seamless pipes, in the following cases and applications:

Factor	Forged Pipe Advantage
Larger OD	Forged pipes show an overall cost advantage for larger OD pipes, say OD > 18” as a rule of thumb
Heavier wall thickness	Forged pipes are the elective choice for applications that require heavy wall thickness pipes, for example from 40/50 mm WT upwards
Special tolerances or surface finishing	Due to its fine manufacturing process, forged pipes can be produced to custom dimensions and precise tolerances (whereas seamless pipes show a constant divergence between actual vs. theoretical sizes)
Small production lots	The minimum order size for a forged mill is just 1 pipe, whereas seamless pipes manufacturers have minimum lot quantities of several tons, generally above 10

On the contrary, Seamless Pipes are more cost-efficient in the following cases:

Factor	Seamless Pipe Advantage
Standard OD sizes	Sizes from 12,7 mm (1/2”) to 457 mm (18”)
Standard wall thickness	Projects requiring pipes with standard wall thickness, for example below 25/30 mm
Large lots	Minimum order is 200 meters / 20 pipes per size

The image below shows the competitive range for forged pipes (vs. seamless pipes) in terms of pipe OD (outside diameter) and WT (wall thickness):

forged pipes competitive range

Typical Cases of Application

Forged seamless pipes are used across multiple industries. The table below lists the most common applications:

Industry	Applications	Why Forged Pipes Are Used
Oil and Gas	Drilling operations, well completion, pipeline construction, transmission of crude oil, natural gas, and refined petroleum products	Withstand high-pressure, corrosive environments, and extreme temperatures in upstream, midstream, and downstream operations
Petrochemical and Chemical	Reactors, heat exchangers, distillation columns, process equipment	Resistance to chemical corrosion and high temperatures when conveying chemicals, acids, and corrosive fluids
Power Generation	Boilers, steam turbines, condensers, heat recovery systems	Transport steam, water, and other fluids at high temperatures and pressures in thermal power plants, nuclear reactors, and renewable energy installations
Aerospace and Defense	Aircraft components, missile systems, military vehicles, hydraulic systems, fuel lines	Lightweight yet strong materials with high fatigue resistance for structural components
Mechanical and Automotive	Shafts, axles, gears, exhaust systems, suspension components, drivetrain assemblies	Superior strength and durability for high-performance precision components
Infrastructure and Construction	Bridges, buildings, tunnels, offshore structures, piling, foundation works	High load-bearing capacity and corrosion resistance
Mining and Exploration	Drilling rigs, wellbore casing, pumping systems, mineral processing plants	Drilling, extraction, and transportation of minerals, ores, and fluids
Marine and Offshore	Offshore drilling, production platforms, subsea pipelines	Withstand harsh marine environments, high pressures, and corrosive seawater conditions

Advantages of Forged vs. Seamless Pipes

Forged pipes have several advantages over seamless pipes, particularly for high-strength and high-reliability applications:

Technical Reasons

High-Pressure Tolerance

Forged pipes are preferred in high-pressure applications. The forging process aligns the grain structure to the pipe shape, increasing resistance to internal pressure.

Improved Mechanical Properties

Forging refines the metal’s microstructure and closes porosity, resulting in better strength, ductility, and toughness. This makes forged pipes well-suited for heavy-duty service.

Chemical Consistency

Forging produces a more homogeneous material with consistent chemical properties throughout the cross-section, which is important for chemical and nuclear industry applications.

Reduced Chance of Defects

Forged pipes are made from a single piece of metal shaped under high pressure, with no welding or seams. This reduces the likelihood of defects such as inclusions, voids, or weak spots that could fail under stress.

Durability in Fluctuating Conditions

Forged pipes typically exhibit excellent fatigue resistance and long-term durability, even in applications where the temperature or pressure may fluctuate significantly.

Custom Alloys

Forging allows the production of pipes from alloys that may not be feasible with standard seamless manufacturing methods, which matters for applications requiring non-standard material properties.

Commercial Reasons

Customization and Sizes

Forged pipes can be produced to custom sizes and thicknesses, which is useful when standard pipe dimensions do not meet project requirements.

Cost-Effectiveness for Small Quantities

For small batch sizes, forged pipes are more cost-effective than seamless pipes because the minimum order quantity is lower (as few as 1 pipe vs. 20+ for seamless).

Where these attributes matter, forged pipes are the preferred option, particularly in oil and gas, power generation, and nuclear energy.

Summing Up

Heavy wall-thickness forged pipes are used in more demanding applications than conventional seamless pipes:

• Power Generation steam lines, for instance, require high chrome content (alloy grade 11, grade 22, grade 91, grade 92) and heavy wall thickness lines to resist the high temperatures generated by the energy production process.
• A controlled ID Diameter pipe allows better dimensioning during the engineering stage, reduces welding costs during pipe installation, and furthermore reduces vortex fluid movements & creep risks inside the piping of the plant.
• Offshore parts subject to High Mechanical Stress like Risers, J-Lay Collars, and Spool Pieces are supplied in X grades (X60/X70). Those parts require high mechanical properties, in particular very high tensile strength at low temperatures (for example: an expected crush with the offshore pipeline could create serious damage to the pipelines) and require very strict machining tolerances (for example: pipelines need to be clean with pigs on a routine basis).
• Another common application of forged pipes is for OCTG Couplings in Upstream applications (for example: couplings for OCTG casing pipes size 18 5/8”) for heavy dimensions & heavy thickness that cannot be produced by using the standard seamless production process.

Some examples of forged steel products for application in the oil & gas, power generation, and heavy manufacturing industries:

Forged J-Lay Collars

Forged Y-Pieces

Forged Spool Pieces

Forged Riser

Manufacturers of Forged Pipes

The forged pipes market is a niche segment populated by a large number of small and medium-sized manufacturers.

The world’s most qualified forgings mills are located in Northern Italy (more than 20 suppliers) and Germany, along with some smaller production sites in China.

For Seamless Pipes, we have identified 2 categories of manufacturers (depending on the steel grade family):

Steel Grade Family	Major Manufacturers	Market Notes
Carbon steel pipes	Tenaris, Vallourec, Sumitomo	Global groups dominate supply; Chinese manufacturers play a smaller role. USA, Saudi Arabia, and Russia see a strong presence of local suppliers with sales limited to their local markets
Stainless steel pipes	Salzgitter DMV, Tubacex, Sandvik	European manufacturers share the market with growing Chinese competition

Here is a list of global-scale manufacturers (multinational companies) known for producing forged steel pipes:

Manufacturer	Origin	Industries Served
Vallourec	France	Oil and gas, power generation, petrochemicals
Tubos Reunidos	Spain	Oil and gas, energy, mechanical applications
Nippon Steel Corporation	Japan	Offshore and onshore oil and gas
TMK Group	Russia	Drilling, exploration, and production (oil and gas)
Tenaris	Argentina/Luxembourg	Oil and gas drilling, refining, transportation
Borusan Mannesmann	Turkey	Energy, construction, automotive, industrial
JFE Steel Corporation	Japan	Oil and gas, mechanical engineering, automotive
United States Steel Corporation (U.S. Steel)	USA	Energy, infrastructure, construction
Sandvik AB	Sweden	Oil and gas, chemical, aerospace
Ovako Group	Europe	Automotive, mining, construction

This list is not exhaustive. Availability of specific products varies by region and market demand.

Please contact us in case you need recommendations based on steel grade, size, and pipe weight.

ASTM Material Grades Forged vs. Seamless Pipes

The table below shows the most common material grades of seamless pipes and their forged equivalent:

MATERIAL TYPE	SMLS PIPE GRADE	FORGED GRADE
CS - Carbon Steel - High Temperature	ASTM A106 gr B / A53 gr B / API 5L gr B/X42 PSL1	ASTM A105
CS - Carbon - Low Temperature	ASTM A 333 gr 6	ASTM A350LF2
CS - Carbon Steel	API 5L gr B / X42 PSL1
CS - Carbon Steel	API 5L gr B / X42 PSL2	A694 F42
CS - Carbon Steel	API 5L gr X42 PSL2
CS - Carbon Steel	API 5L gr X52 PSL1
CS - Carbon Steel	API 5L gr X52 PSL2	ASTM A694 F52
CS - Carbon Steel	API 5L gr X65 PSL1
CS - Carbon Steel	API 5L gr X65 PSL2	A694 F65
CS - Carbon Steel - Galvanized	ASTM A 53 gr. B	ASTM A105
AS - Alloy	ASTM A 335 P11	ASTM A182 F11
AS - Alloy	ASTM A 335 P22	ASTM A182 F22
AS - Alloy	ASTM A 335 P5	ASTM A182 F5
AS - Alloy	ASTM A 335 P9	ASTM A182 F9
AS - Alloy	ASTM A 335 P91	ASTM A182 F91
SS - Stainless	ASTM A 312 TP304-304L	ASTM A182 F304-F304L
SS - Stainless	ASTM A 312 TP316-316L	ASTM A182 F316-F316L
SS - Stainless	ASTM A 312 TP321	ASTM A182 F321
SS - Duplex 22	ASTM A790 UNS S31803	ASTM A182 F51
SS - Superduplex 25	ASTM A790 UNS S32750 / 32760	ASTM A182 F53 / F55
SS - Inconel - Nichel Alloy 6625	ASTM B444 UNS N06625	ASTM B564 UNS N06625
SS - Inconel - Nichel Alloy 8825	ASTM B423 UNS N08825	ASTM B564 UNS N08825
CUNI - Cupronickel (CuNi 90/10)	ASTM B466 UNS C70600	UNS C70600
CUNI - Cupronickel (CuNi 70/30)	ASTM B466 UNS C71500	UNS C71500

Conclusion

Forged steel pipes are used across many industries for transporting fluids, gases, and solids in demanding environments. Their controlled manufacturing process, tight dimensional tolerances, and guaranteed minimum wall thickness make them the preferred choice over seamless pipes for large-diameter, heavy-wall, and safety-critical applications (offshore, nuclear, high-temperature steam lines). For standard sizes and large production lots, seamless pipes remain more economical.

Pro Tip

Specify forged pipes when you need guaranteed minimum wall thickness. Seamless pipes are manufactured OD-controlled with average wall thickness (can be -12.5% under nominal), while forged pipes are ID-controlled with minimum wall guaranteed. For pressure calculations where minimum wall is critical, forged pipes eliminate the uncertainty.

Common Mistake

Ordering forged pipes when standard seamless would suffice. Forged pipes cost significantly more due to the intensive machining process. They’re justified for heavy walls (>40mm), large diameters (>18”), nuclear/offshore applications, or small lot sizes - but for standard sizes in quantity, seamless is more economical and equally suitable.

Field Note

When receiving forged pipes, verify the machined surfaces meet the specified surface finish (typically Ra 3.2 μm or better). Poor machining can leave tool marks that act as stress risers under pressure cycling. Run your hand along the bore - it should feel uniformly smooth without ridges or grooves.