1. (General Engineering) tungsten-electrode inert gas welding: a method of welding in which the arc is maintained by a tungsten electrode and shielded from the access of air by an inert gas. Compare MIG welding.
A prescription for a controlled drug is valid for 28 days from the date given on the prescription. usually six months unless it's a controlled i.e. morphine, pethidine and methadone. These medicines are often misused, so have stricter legal controls on their supply to prevent them being obtained illegally. A prescription for a controlled drug is valid for 28 days from the date given on the prescription.
Your Eyeglass Prescription Expiration After a visit to the eye doctor, you will get a prescription if you need corrective lenses. The prescription will only be valid for a fixed time; eyeglass prescription expiration periods vary but are usually one to two years. The expiration date is the last day that your prescription can legally be used by optical shops and labs to make glasses or provide contact lenses.