Complex sentence: Glass-metal seals commonly fail by forming radial cracks that originate at the pin-glass interface and permeate outwards; other causes include a weak oxide layer on the interface and poor formation of a glass meniscus around the pin.
Split into simpler sentences: Glass-metal seals commonly fail by forming radial cracks. The cracks originate at the pin-glass interface and continue outwards; other failure causes are a weak oxide layer on the pin-glass interface, and poor formation of glass meniscus around the pin.