I have some 8" air cooled martin fireplace chimney pipe. It has an 8" stainless pipe inside an 11" outer galv pipe. Thiis is an aircooled chimney. There is a sticker on the side that says it is ul rated. It says issue # u262 and 586. Are these ul standards and what do they mean? Trying to determine if this is a safe modern chimney pipe. I beleive it is around 10 years old. Thanks