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Reducer (Variable-Diameter) Straight Thread Couplers —
The Professional Solution for Connecting Rebars of Different Diameters
In real construction projects, have you ever faced this situation:
two rebars need to be connected, but their diameters are different, and standard couplers simply don’t work?
That’s exactly where reducer-type (variable-diameter) straight thread couplers come into play.
However, this type of coupler is not suitable for every situation. Today, we’ll explain in detail under what conditions reducer-type straight thread rebar couplers should be used, so you can choose the right connection method with confidence.
Common Application Scenarios for Reducer-Type Straight Thread Couplers
When Structural Forces Change and Rebar Diameters Need to “Transition”
In many building structures, load conditions vary with height or span, which means the rebar diameter must change accordingly. In these cases, reducer-type couplers are not optional—they are essential.
Typical examples include:
High-rise building frame columns
Lower floors bear the weight of the entire structure and usually require larger-diameter rebars, such as Φ36 mm or Φ40 mm.
As the building rises, structural loads decrease, allowing the use of smaller rebars like Φ32 mm or Φ28 mm.
When these different diameters must be connected, reducer-type couplers ensure smooth force transfer and structural continuity.
Frame beams: supports vs. mid-span sections
At beam supports, stress concentration requires larger-diameter rebars.
In mid-span areas, where forces are lower, smaller-diameter rebars are sufficient.
Reducer-type couplers enable reliable connections between these rebars while avoiding stress concentration and abrupt stiffness changes.
In short, whenever rebar size must change due to structural design requirements, reducer-type straight thread couplers provide a safe and efficient connection solution.
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Important Notes on GULISI Reducer-Type Straight Thread Couplers
To meet the needs of most construction projects, GULISI adopts a standardized inventory strategy for reducer-type straight thread couplers.
Regular stock covers reducer couplers with diameter transitions of up to three size grades, such as:
Φ20 → Φ25
Φ28 → Φ22
These specifications can directly meet the majority of structural rebar transition requirements, ensuring fast availability and immediate use on site.
Custom solutions for special requirements
If your project involves non-standard diameter combinations or transitions exceeding three size grades, custom-designed couplers are required.
In such cases, please contact the GULS team in advance to confirm:
Rebar specifications
Required quantities
Delivery schedule
Customized production ensures precise thread parameters, proper mechanical performance, and full compatibility with special construction demands.
