gasu no kaituu no zikan wo kakuninsimasita.

Normally, Japanese is written without spaces:

ガスの開通の時間を確認しました。

The spaces in your example are just a learner aid to make the parts easier to see.

開通 means something like connection, activation, or service starting.

In this sentence, it does not mean gas physically moving through a pipe at that moment. It means the gas service being turned on or made available.

A small nuance point: for gas service specifically, native speakers often use 開栓 instead of 開通. So ガスの開栓時間を確認しました may sound more natural in everyday utility-related Japanese.

Both の are linking nouns together.

You can think of it in steps:

• ガスの開通 = the gas activation / the opening of the gas service
• ガスの開通の時間 = the time for the gas activation

So the whole noun phrase is built like this:

• ガス → gas
• 開通 → activation/connection
• 時間 → time

Japanese often stacks nouns this way.

Yes. A more compact version is:

ガスの開通時間を確認しました。

This removes one の and sounds smoother.

Also, if you want the most natural utility-related wording, many speakers would say:

• ガスの開栓時間を確認しました。
• ガスの開栓予定時刻を確認しました。

So your original sentence is understandable, but there are slightly more natural alternatives.

Because 時間 is the direct object of 確認しました.

The pattern is:

• X を 確認する = to check / confirm X

So here:

• 時間を確認しました = confirmed the time

Everything before 時間 just describes what kind of time it is.

Here it most likely means the scheduled time or time slot, not a duration.

So it means something like:

• what time the gas service will be activated
• the appointment time for turning on the gas

Even though 時間 can sometimes mean length of time, context is very important. With 確認しました, the natural reading here is I confirmed the time.

確認しました is the polite past form of 確認する.

It means the action of checking/confirming has already been completed:

• 確認します = I will confirm / I confirm
• 確認しました = I confirmed / I have confirmed

In Japanese, the past form is very commonly used when simply reporting that you already did something.

The subject is omitted, which is very normal in Japanese.

So depending on context, it could mean:

• I confirmed the time
• We confirmed the time
• sometimes even He/She confirmed the time

In isolation, English learners often translate it as I confirmed the time, because that is a natural default when someone is reporting their own action.

No. In this sentence, ガス means gas service for a home or building—the utility used for cooking, heating, and so on.

So this is about a utility company turning the gas on, not about fuel for a car.

It is read:

ガスのかいつうのじかんをかくにんしました。

Word by word:

• ガス = がす
• 開通 = かいつう
• 時間 = じかん
• 確認しました = かくにんしました

If you use the more common gas-related word 開栓, that reading is かいせん.