I am not sure of the wages in your area but another factor that comes into play is whether or not you are utilizing your own equipment/shop facilities to do all testing or if you're simply are called to a facility to conduct visual inspections prior to other nondestructive and destructive testing which will be done else-ware.
Personally, my standard rate for VT, PT or MT is $100/hour for local jobs. If I were to have to travel and stay multiple days it's $100/hour + the standard federal rates for food and lodging + federal standard rates for mileage to and from the facility. In these cases, I do not charge for mileage from hotels and around town travel while traveling to work each day.
r/
David