I'm assuming sched 40 bulkheads....I've never had a problem with them leaking, but as Al stated usually tighter than hand tight. That's why I honestly spend the extra time; money on sched 80 just for the extra thick gasket and beefy body of the bulkheads itself. No lubed needed for the gasket, and I know some might say/suggest silicone, but very bad idea. I'm sure you know gasket on wet side, but double check, also make sure nothing underneath the gasket as well.