Question: are ips and nps the same?
Answer: The IPS number (reference to an OD) is the same as the NPS number, but the schedules were limited to Standard Wall (STD), Extra Strong, (XS) and Double Extra Strong (XXS). STD is identical to Schedule 40 for NPS 1/8 to NPS 10, inclusive, and indicates . 375" wall thickness for NPS 12 and larger.