Question: what is the difference between std and sch 40?
Answer: STD is identical to SCH 40S, and 40S is identical to 40 for NPS 1/8 to NPS 10, inclusive. ... XXS wall is thicker than schedule 160 from NPS 1/8 in to NPS 6 in inclusive, and schedule 160 is thicker than XXS wall for NPS 8 in and larger.