Hi Jbrotzman!
Weldcome to the forum!
As far as "J" grooves are concerned, on the welding symbols, a broken arrow is usually attached to the reference line. The reason for the broken arrow is to point specifically to the only member of the joint that needs preparation prior to welding...
It is VERY important to position or orientate the welding symbol on the drawing so that the persons responsible for fabrication and/or welding interprets the drawing clearly enough so that there is no ambiguity as to which member of the joint in question, needs preparation. If for whatever reason, this cannot be accomplished, then a detail drawing referring to the joint in question "should" accompany the first set in order to avoid any confusion in certain circumstances.
Another instance whereby a detail drawing is definitely required of the joint in question, is when a specific taper or radius dimension (angular) or a specific depth or width (linear) dimension must be maintained within the shape of the "J" groove preparation itself. Examples of this is when one is working to a specific welding code. As John Wright mentioned previously, if one is working within the parameters of prequalified PJP & CJP welding procedure specifications or WPS's, one does not have to refer to a detail drawing other than the one(s) shown in the prequalified WPS('s) because on the welding symbol itself, the tail attached to the reference line will have the reference to the specific prequalified WPS.
Some examples would be to find a "BC-P8**" or a "BTC-P9-GF**", "BU-8", "TC-U8-GF", or a "BU-9", TC-U9a-GF in the tail section of the welding symbol. The person(s) responsible for fabrication/welding will then be able to refer to the specific prequalified welding procedure specification for joint preparation.
However, if the design requires that the joint preparation dimensions be above or below the specific parameters found in the prequalified WPS's, then a qualification of the joint must be done and a detail drawing "should" accompany the final drawing(s)...
All of these factors should be considered when deciding whether or not a detail drawing of the joint is required and in choosing the appropriate elements to include in the welding symbol that accompanies the detail. In the tail attached to the reference line on the welding symbol, there should be a reference to the specific detail drawing if the welding symbol is to be placed in the EOR (Engineer Of Record) approved drawing(s), provided that everything else mentioned above is considered.
Finally, if you're working to a specific welding code, then BUY a copy of the welding code!!! It will make your life a whole lot easier :)
Respectfully,
SSBN727
Run Silent... Run Deep!!!