self-seal
A self-sealing pipe, tyre, container, etc. can automatically seal(= close) small holes in its surface: （管道、轮胎、容器等）自动密封的
I'm prepared to bet those pipes are self-sealing.我敢打赌这些管道是自动密封的。
The aircraft are fitted with self-sealing tanks and enhanced armour protection to make them combat capable.这些飞机配备了自密封油箱和强化的防护装甲，使其具备作战能力。
A self-sealing substance forms a cover or structure that prevents air, water, etc. from entering or leaving it. : 能形成（防止渗漏的）保护层的
I ordered 4 bags of self-sealing cement.我订购了4袋自愈合水泥。

SMART Vocabulary: related words and phrases

Bags in general
bag
bag for life
bagful
carrier
carry (something) on
doggy bag
feedbag
man bag
nosebag
packet
party bag
pencil case
polybag
pouch
self-seal
shopper
shopping trolley
string bag
stuff bag
Ziploc

You can also find related words, phrases, and synonyms in the topics:

Letters, notes and cards
Closing and blocking