You can find more about SOPEP under Annex I, SMPEP on the other hand is under Annex II of MARPOL 73/78. Thus, SOPEP covers the prevention of pollution arising from an oil pollution incident and SMPEP prevents or controls pollution by Noxious Liquid Substances or chemicals.
Do all ships have SOPEP and SMPEP?
“Every oil tanker of 150 gross tonnage and above and every ship other than an oil tanker of 400 gross tonnage and above shall carry on board a shipboard oil pollution emergency plan approved by the Administration.”
“Every ship of 150 gross tonnage and above certified to carry noxious liquid substances in bulk shall carry on board a shipboard marine pollution emergency plan for noxious liquid substances approved by the Administration.”
Now what if vessel is carrying both oil as well as chemical ?
Vessels certified to carry oil and noxious liquid substances can only have an approved Shipboard Marine Pollution Emergency Plan (SMPEP) in accordance with regulation 37 of Annex I and regulation 17 of Annex II.