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arrow.gif (560 bytes)Mandrels for Bend Testers


How to Determine the Bend Radius (and Mandrel) for Your Application

bend test jigs


Three factors determine the bend radius to be used. These are:

  • the code or standard,
  • the material being welded, and
  • the thickness.

Each code and standard lists the required bend radius and the associated roller spacing to be used for a given material and thickness. The following paragraph references are from several popular codes and standards:


Code or Standard Bend Radius Description of the Test
Guided Bend Wraparound
ASME Section IX-17 Fig. QW-466.2 Fig. QW-466.3 Parag. QW-160
API 1104 2013 Fig. 8 NA Parag. 5.6.4, 5.6.5
AWS B2.1:2014 Fig. A.5A Fig. A.5C Parag. 4.7.6
AWS D1.1:2015 Fig. 4.13 Fig. 4.12 Parag.

None of the commercial or military codes or standards requires you to bend any specimen thicker than 3/8 inch (1/2 inch for API 1104). Even if you are testing 1-1/2 inch thick material, the codes instruct you on how to prepare side bend specimens which are only 3/8 inch thick (1/2 inch for API 1104). These 3/8 (1/2) x 1-1/2 inch side bend specimens are easily bent using a 1-1/2 inch diameter mandrel (3-1/2 inch for API 1104).

Why Fischer Mandrels and Mandrel Adapters are Special

All mandrels are hardened tool steel. All BT1 Series mandrels include our patented, knurled surface,  to reduce the possibility that the specimen will slip sideways during bending. This works in most cases. For severe cases of dissimilar weld and base metals, either longitudinal bend specimens or the Model BT3 Bend Tester is the better choice.

The numerical portion of the mandrel part number is the mean outside diameter, in inches, of the mandrel. The smaller mandrels require an adapter.

We have the largest selection of standard mandrel sizes in the industry. Please see our price sheet for a listing. For special sizes, call for price and delivery. We may have already made the size you need. If not, we can!


  • BT1 Series Mandrels
  • BT3 Series Mandrels

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Last modified: 1-10-18