IIW History 1948-1958

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at it plenary session in 1953, became a Drajt I SO R ecommendation wh ich ena– bled the various national st andards Committees t o revise their respective st an– da rds dealing with covered electrodes a nd t o bring them into line, with a view t o international unification , with the stipulations of the Code of Symbols. Thi Code, as it was adopted, envisaged the development of a met hod fo r e t ablish ing the hydrogen content in met al deposited by basic elect rodes. This question has already been raised in connexion with the wo rk of Sub-Commission _.\.. But, as a result of investigations undertaken, Commission n has heen led t o suggest the following arrangements : r. That , with regard t o the h ydrogen content of weld met al, r efe rence should not be made only t o electrodes with a basic covering. 2. That a special ymbol H , which \\ ould be placed at t he encl of the desig– nation by symbols, should be adopt ed fo r low hyd rogen electrode . 3. That the hydrogen content of elect rodes receiving the symbol H must be below 5 cm 3 of hydrogen per r oo g of weld met al. 4. That t he symbol H should not be used fo r electrodes of 0 -type covering, even if the metal deposited by t hese elect rodes meet s t he conditions imposed . F inally, Sub-Commission E has had t o con ider other questions raised by I SO, such as those in connexion with the qualifica tion of an operating method which affect ed Sub-Committee 3 of the Technical Comittee I SO/TC II (Unifi– cation of Boiler Codes) . _.\. . Sub-Commiss ion A « Hydrogen i n Weld Metal » . r. I nvestigation on a t est suitable fo r distinguishing low hyd rogen elec– t rode . The t est s \vill be carried out using ten t y pes of elect rode in six labora– t ories, five differe nt methods of t esting being used. The t est s will include : a) the det ermination of t he diff usible hyd rogen, b) the determination of t he total hydrogen content , c) t he det ermination of t he moisture content of coverings, st ored a t a t empera– ture of 150° C, d) the det ermination of the moisture and the t ot al h ydrogen at rooo° C, e) the measurement of t he te ndency to underbeacl cracking, /) the measurement of t he t endency of the weld met al t o crack. z . Studies on microfissures clue to h ydrogen in conjunction with the degree of rest raint and the speed of cooli ng. 3. Test s fo r det ermining the stresses above which