Pipe clamps (also called aligners) secure and align pipe ends before welding. GBC offers four main families: bridge clamps for small and medium diameters; cage clamps for fixed diameters with heavy welding; chain clamps for large diameters with reforming capability; internal expansion systems for flanges, elbows, and complex geometries. The choice depends on diameter, material, joint type, and reforming requirements.

What pipe clamps are used for

Before a welder strikes an arc, the two pipe ends must be perfectly positioned: coaxial, with a uniform root gap and no internal misalignment. This misalignment — where one pipe wall protrudes relative to the other — is called Hi-Lo and is one of the most common defects in welded joints. In sectors such as oil & gas and pipelines, where joints undergo 100% radiographic or ultrasonic inspection, excessive Hi-Lo results in automatic rejection and rework.

The issue goes beyond dimensional tolerance. Even minimal misalignment alters weld root geometry, reduces joint strength, and creates stress concentrations that accelerate material fatigue. In pressurized systems or extreme temperatures, consequences can be critical.

Clamps solve this mechanically by holding components in position during tack welding and, in some cases, actively correcting pipe geometry before welding. Without them, alignment would require improvised setups, multiple operators, and significantly longer cycle times. In serial production and pipeline construction, they reduce both time and operational costs.

A key distinction is between external clamps, which act on the outer surface, and internal ones, which expand outward from inside the pipe. External clamps are more versatile and faster to apply; internal systems ensure alignment based on the internal diameter, which is crucial when internal geometry is critical (e.g., fluid pipelines where irregularities may cause turbulence or buildup).

Another distinction concerns reforming capability: some clamps simply hold correctly shaped pipes, while others actively correct ovality and deformation by applying controlled force along the circumference.

Bridge clamps: fast centering for small and medium diameters

Bridge clamps are the most common solution for diameters up to 14″. They are placed over the joint and tightened from both sides via a screw system. Centering is immediate: position, tighten bolts, and the joint is ready for tack welding. Their light weight allows single-operator use even in difficult positions. They are standard in workshops handling small to medium diameter pipes in carbon steel, stainless steel, and special alloys, as well as in maintenance and field work.

 

GBC offers two versions with distinct construction features.

Gold Bridge Clamps are made of forged steel for maximum strength and durability. The wing bolts feature stainless steel bearings. They cover a range of 1″ to 14″ across five models: GBC3 (1″-3″), GBC5 (2″-5″), GBC7 (4″-7″), GBC9 (5″-9″), and GBC14 (10″-14″). They are designed for general use on carbon steel. For applications on stainless steel or materials sensitive to carbon contamination, a stainless steel cover kit is available that quickly mounts to the contact points. For a more in-depth technical discussion of this model, see our dedicated article on Gold Bridge Clamps.

Black Bridge Clamps come standard with stainless steel locking feet, making them directly compatible with stainless steel, duplex, super duplex, and titanium without the need for additional kits. They cover 1″ to 12″ (25.4-304.8 mm) in three models: BBC2 (1″-2″), BBC6 (2″-6″), and BBC12 (5″-12″). The design distributes the clamping force evenly around the tube—the distance between the clamping points is the same for all sizes in the range—ensuring consistent centering regardless of diameter. Tube-to-tube and tube-to-fitting welding is easily performed on both sides of the joint.

Cage clamps: fixed-diameter alignment for heavy-duty welding

Cage clamps work on a different principle: they completely enclose the pipe with a rigid cage structure that ensures precise alignment. Each model is designed for a specific diameter, yet offers an extremely stable grip, even in harsh conditions. The closed structure also makes them less susceptible to dirt and mud, an important aspect on construction sites.

GBC offers three versions for different needs:

• Manual Cage Clamps (range 4″-24″): the solution for welding and workshops for smaller diameters. They maintain high precision at low costs.
• Ratchet Cage Clamps (range 12″-60″): Featuring a ratchet mechanism for quick tightening and superior holding power. The standard 1″ handle fits all sizes in the range.
• Hydraulic Cage Clamps (range 20″-60″): for applications requiring maximum clamping power and consistent holding on challenging materials and thicknesses.

Cage clamps find their ideal context in welding on fixed systems, shipbuilding, heavy carpentry and wherever work is carried out in series on pipes of the same diameter..

Chain clamps: large diameters and reformation

For large diameters, bridge and cage clamps are no longer usable. Chain clamps solve the problem: a chain wraps around the pipe and, via jackbars, applies targeted forces to align and reform the pipe, correcting ovalities and Hi-Lo defects before welding. It is the reference technology for pipelines, large industrial plants, and shipbuilding.

A significant logistical advantage: a single GBC chain clamp covers the equivalent range of eight cage clamps. This means a much more streamlined tool park and simplified inventory management, especially for those working on orders with variable diameters.

GBC Single Chain Clamps cover 4″ to 48″ depending on the model chosen: the SCC12 and SCC24 start at 4″ (101.6 mm), while the SCC36 and SCC48 start at 10″ (254 mm). Each model mounts a calibrated number of jackbars: from 4 jackbars for the 12″ models up to 12 for the 48″ model. The joints are completely welded without removing the clamp thanks to the tack-free jackbar configuration. Elbows, T-pieces and other fittings are precisely aligned using the included fitting alignment device. Available in carbon steel and stainless steel versions..

Double Chain Clamps take capabilities to the next level. The range extends up to 72″ (1829 mm) with the DCC72 model, which accommodates 20 jackbars. The extra-heavy-duty, independent jacks allow for alignment of the inside and outside diameters within 0.5 mm, an accuracy that is far from guaranteed on these diameters. They reform pipe up to Schedule 80 on both sides of the joint, and handle elbows, tees, and other fittings that cage clamps cannot handle. Double Chain Clamps are also available in stainless steel across the entire model range (DCC24, DCC36, DCC48, DCC60, DCC72).

Chain clamps are widely used in the oil & gas, petrochemical, and pipeline sectors, where diameters are large, thicknesses are significant, and joint quality requirements are extremely stringent. On pipeline construction sites, the ability to reform the pipe directly on site, without returning it to the workshop, eliminates a step that in some contexts would require hours of work.

Internal Systems and Pincer Clamps: FTE, FTP, and Quick Alignment

When the joint involves a flange, an elbow, a curved pipe, or two elements of different diameters, internal expansion systems often become the only truly practical and precise solution. They are inserted inside the components and expand toward the internal wall to lock them in place, ensuring coaxial alignment and leaving the outside of the joint completely free for welding. They are made entirely of stainless steel and belong to the SS Ready series, meaning they are ready for use on stainless steel without the risk of carbon contamination.

The FTE Clamps SS Ready are designed for the simultaneous clamping of a flange and a curved pipe, elbow, or other non-straight geometry. The system consists of two independent expansion clamps: the lower one fits into the bend and is tightened via a knob, while the upper one secures the flange via a manual bar. Available in four sizes, they cover a range from 54 to 520 mm. The two-clamp configuration allows for any differences in diameter between the components to be compensated for.

FTP Clamps SS Ready solve the problem of aligning two hollow cylindrical components of different diameters on the same centerline, such as a nozzle on a tank, a fitting on a pipe, or a concentric reducer. In this case, too, the system uses two independent expanders: the lower one is inserted and locked into the first component via a knob, while the upper one secures the second via a manual bar. The range covers 54 to 940 mm in five sizes (FTP140SS, FTP220SS, FTP350SS, FTP520SS, FTP940SS), making them suitable for a wide range of applications in the petrochemical, energy, and plant engineering sectors.

Pincer Clamps SS Ready operate externally via a clamp mechanism, but share the FTE and FTP’s all-stainless steel construction and compatibility with sensitive materials. They offer a distinctive feature compared to the FTE and FTP systems: automatic diameter compensation. Manual adjustments are not required as the pipe diameter changes, as the system automatically adapts, significantly reducing setup times. They allow pipes of the same or different diameters to be aligned on a common centerline, keeping all parts easily accessible during welding. They are available in three sizes (PC70SS: 10–70 mm, PC140SS: 40–140 mm, PC330SS: 75–330 mm) and are particularly suitable for workshops with high production variability or on sites where different configurations are frequently switched.

Materials: which version to choose

The choice of coupler material is crucial. On stainless steel, duplex, superduplex, and titanium, any contact with carbon steel can cause iron contamination, triggering localized corrosion on the tube surface, precisely at the most critical point: the weld joint. In the pharmaceutical, food, petrochemical, and naval sectors, this type of contamination can lead to rejection of the entire component.

For this reason, GBC offers stainless steel solutions across its entire range: Black Bridge Clamps with standard stainless steel feet, SS models of chain clamps (SCC and DCC), and the entire FTE/FTP/Pincer line already manufactured in stainless steel. For Gold Bridge Clamps used on stainless steel, the optional stainless steel cover kit eliminates the need for complete clamp replacement.

How to choose the right clamp: practical criteria

To identify the most suitable solution, it is necessary to answer four fundamental questions:

What is the pipe diameter? For diameters less than 14″, bridge clamps cover most applications. Between 4″ and 60″, cage clamps are ideal when the diameter is fixed and production is serial. From 4″ to 72″, chain clamps are the solution for more complex cases, including large diameters and situations with high variability. For diameters less than 330 mm with complex geometries or the need for quick alignment, pincer clamps are often the most efficient choice.

Is the tube ovalized or deformed? If so, you need to use a chain clamp with a reshaping function.

What materials can be welded? For stainless steel, duplex, superduplex, and titanium, it’s essential to select versions with stainless steel contact parts: Black Bridge Clamps, SS chain clamp models, or the FTE/FTP/Pincer line. For carbon steel, standard versions are generally sufficient.

What is the joint geometry? For straight tube-to-tube joints, bridge, cage, or chain clamps are used depending on the diameter. For tube-to-flange or tube-to-elbow joints, FTE or FTP internal expansion systems are used. To align different diameters, FTP clamps or pincer clamps are used. When frequent diameter changes occur, pincer clamps with automatic compensation are the most efficient solution.

The comprehensive range of GBC clamps covers a clamping range from 10 mm to 1829 mm (72″), with solutions for every combination of diameter, material and joint geometry. For non-standard applications or if you are unsure about your selection, please contact our technical team.