No dues/fees, other than travel costs for meetings. I don't think you even really have to be an AWS member though they'd probably prefer it.
Minimal duties are show up, read your email, vote. If you're a good member, show up, volunteer for task groups, complete your tasks, read your email, use logic, understand compromise, read carefully, vote.
The only absolute qualification is related job experience. Not everyone's an engineer; not everyone's a welder. Different committees may have different requirements.
Looking at the online list...I don't know much about any of them other than D1, but for D1 that looks like a complete list of the subcommittees. D1A through D1E got demoted to standing task groups under D1Q, the subcommittee for the D1.1 book. But those task groups also might be looking for members, and they've still retained traces of the old subcommittee process even with the new task group system. I'm really not sure how it works any more, whether membership on those standing TGs automatically makes one eligible for D1Q membership, whether they control membership on the TGs as closely as they controlled it when they were still subcommittees, etc. Best bet is to contact the committee secretary and ask.
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There are no base qualifications required; however, it helps if you know something about the scope of the work the committee is addressing.
Members are expected to attend meetings. The number of meetings varies depending on the committee. Some meet 4-5 times a year, others never. How never? Some committees only meet via teleconference. But if you want to be on a committee that does meet then you will need to find a way to pay for travel and accommodations for the meeting. AWS does not pay for travel or accommodations for committee members. The support of your company is really helpful with this.
Committee members receive documents via email that you need to review and vote on. If a member does not vote frequently enough they can be booted from the committee for not fulling their obligation to review and vote on documents. This may mean reviewing and voting on documents that you were not personally involved with if the document is coming from a committee subordinate to the one on which you are a member. Members on lower level committees in the AWS "tree" do not have to really worry about this; members on higher level committees may have many committees beneath them requiring review of dozens of documents a year.
There are no dues or fees to become a member but committee officers must be AWS members so there is the cost of the AWS membership to consider if you want to chair an AWS committee. There is also the cost of travel mentioned above to consider as well.
The committee list includes all the technical services committee or the committees responsible for producing AWS standards. It contains all the ones that I am familiar with; I don't see any obvious omissions. Committees for the Welding Handbook, Certification programs, Education programs and such are not technical committees, per se, so they are not on this list; however, if you are interested in a committee not on the list put it on the application. I'm sure it will get routed to the right person. Membership on the highest AWS committees, such as the Board of Directors, is done either through elections, nominating committees, or appointment by other AWS members in high level offices.