Heavy-plate U and J grooves for pressure vessel shells

GMMA-100L and GMMA-100U machines mill deep U and J grooves on 60–100 mm shell plate, cutting filler metal compared with a V-groove.

Industry: Pressure vessels
Machines: 3

Heavy-plate U and J grooves for pressure vessel shells

The challenge

On thick shell plate a plain V-groove opens up very wide, which multiplies the filler metal and welding hours. U and J grooves solve that but are hard to produce accurately with a torch, and alloy steels need any heat-affected material removed before welding.

The solution

The GMMA-100U mills the U-groove root radius directly with a Ø100 mm cutter, while the GMMA-100L handles J-preps and deep V-bevels up to 100 mm wide on 8–100 mm plate. Both cut cold, so there is no heat-affected zone on Cr-Mo material. Nozzle flanges are faced afterwards with a TFS-I1000.

Workflow

Plates are laid out and the joint geometry confirmed against the WPS
Root radius and groove are milled in several passes
Bevel angle and land are checked with gauges at intervals
Shells are rolled and longitudinal seams welded
Nozzle flange faces are machined to finish after welding

Outcome

Grooves with consistent root radius and land are produced straight from the machine, and welders deposit less filler on each seam than with an equivalent V-groove.