MMA electrode with rutile flux on matching core wire. Recovery is about 110% with respect to the core wire, and 65% with respect to the whole electrode. Ultramet 308H gives both welder and weld metal all the benefits of advanced rutile electrode design. These features include optimum versatility for downhand and positional welding, combined with a high cosmetic finish and full volumetric weld metal integrity. The smaller sizes are particularly suited to vertical and overhead welding applications including fixed pipework. In addition, the 2.5mm diameter is specifically designed to enable the root pass to be deposited in single-side butt welds using standard MMA equipment without a gas purge.
Applications
The 308H consumables are designed to match unstabilised 18Cr-10Ni austenitic stainless steels for elevated temperature strength and oxidation resistance. These steels and the weld metal have carbon content controlled to 0.04-0.08%. Composition limits of the MMA electrodes and FCAW wires are tightened above those of BS/AWS specifications to meet the requirements of Shell and other operators of refinery equipment. Weld metal Cr and Ni are kept low and ferrite is controlled to minimise embrittlement by the sigma phase. Beneficial and detrimental minor elements and residuals are also controlled to optimise high-temperature properties. No bismuth-bearing constituents are allowed in these consumables, to ensure <0.002% Bi as required by API 582. The 308H consumables should also be considered for welding thick (>12mm) stabilised grades 321H or 347H to avoid in-service HAZ cracking and low creep rupture ductility associated with 347 weld metal. Note that some authorities recommend the use of type 16-8-2 types for these steels, including 304H. 308H is widely used in petrochemical and chemical process plants, particularly for the fabrication of cyclones, and transfer lines used to re-circulate the catalyst in catalytic crackers (cat crackers) operating in the range 400-815°C.
Specification
AWS A5.4: E308H-16
BS EN 1600: E 19 9 H 3 2
BS 2926: 19.9.R
DIN 8556: (E 19 9 R 23)