Unrivalled Controlled Bollting & Joint Integrity Expertise from HTL Group. HTL Group are controlled bolting and joint integrity specialists. Headquartered in the North East of England with strategically located facilities across the globe, HTL offers a range of products, equipment services and training solutions focussed primarily on bolting & joint integrity operations. Alongside HTL�s extensive range of products and services, our second to none customer service ensures customers continue to choose HTL as their preferred partner to solve any challenges they face.