ang ement ▁ 3 ▁instead ▁of ▁double ▁in ▁the ▁API ▁ 6 8 2 ▁standard . ▁ ▁Se al ▁pip ing ▁plans ▁ ▁An ▁end - face ▁mechanical ▁se al ▁generates ▁heat ▁from ▁rub bing ▁and ▁vis c ous ▁she ar ▁and ▁must ▁be ▁co o led ▁to ▁ass ure ▁good ▁performance ▁and ▁reliable ▁operation . ▁ ▁Typ ically , ▁cool ing ▁is ▁provided ▁by ▁circul ating ▁fluid ▁around ▁the ▁se al . ▁ ▁This ▁fluid , ▁known ▁as ▁a ▁flush , ▁may ▁be ▁the ▁same ▁as ▁the ▁fluid ▁being ▁se aled ▁or ▁an ▁entirely ▁different ▁fluid . ▁The ▁flush ▁may ▁be ▁he ated , ▁filtered ▁or ▁otherwise ▁treated ▁to ▁improve ▁the ▁operating ▁environment ▁around ▁the ▁se al . ▁ ▁Collect ively , ▁the ▁flush ▁and ▁tre ating ▁systems ▁are ▁known ▁as ▁pip ing ▁plans . ▁ ▁P ip ing ▁plans ▁for ▁mechanical ▁se als ▁are ▁defined ▁by ▁American ▁Pet role um ▁Institute ▁specification ▁ 6 8 2 ▁and ▁are ▁given ▁a ▁number . ▁ ▁Some ▁pip ing ▁plans ▁are ▁used ▁for ▁single ▁se als ▁and ▁some ▁only ▁for ▁multiple ▁se als . ▁ ▁Some ▁pip ing ▁plans ▁are ▁intended ▁to ▁provide ▁a ▁means ▁of ▁monitoring ▁the ▁se al . ▁ ▁Some ▁se aling ▁systems ▁include ▁more ▁than ▁one ▁pip ing ▁plan . ▁ ▁See ▁the ▁table ▁below ▁for ▁a ▁summary ▁and ▁description ▁of ▁pip ing ▁plans . ▁ ▁Orig ins ▁and ▁development ▁The ▁mechanical ▁se al ▁appears ▁to ▁have ▁been ▁invent ed ▁by ▁George ▁J . ▁Co oke ▁▁ ▁His ▁design ▁was