Thai fittings should be renamed "cockinabucket" fittings theyre really krap threads.........youll need about 18-20 turns of ptfe starting thin build up to a pyramid shape at the end, always buy the fittings with the metal insertplastic ones again are krap, not perfect but better, then also add green pipefitting dope as mentioned ........ Before fitting the tap try it dry to calculate HOW MANY revolutions get you near to the upright position so when you do tighten it you know how many before it bottoms out. Half inch fittings are the worst it gets better with 3/4 inch for leaks and or splitting when over tight
https://www.lazada.co.th/products/permatex-no51h-118-ml-100-i262179393-s403657700.html?exlaz=d_1:mm_150050845_51350205_2010350205::12:17724336665!!!!!c!!403657700!531910104&gclid=CjwKCAjw9NeXBhAMEiwAbaY4llLOcTVQBZ4l4hk98iJfdT1pO8Td2tQEo7MtxSkgJcbn2d05ITmIehoC-RAQAvD_BwE