How are pipes replaced during a puncture through the road?

Good morning. In general, your question is fully regulated by law.

1) "How are pipes replaced during a puncture through the road?"
 
The first document is “TTK. Laying engineering networks through the carriageway of roads and railways. TYPICAL TECHNOLOGICAL CARD. Technological map for laying engineering networks through the carriageway of automobile and railway roads. ”

Here, the order of work is completely voiced, how this all happens and the requirements for materials. Be sure to check out, this will help you avoid multiple design changes for approval. It also contains the answer to your 1 question - how is the process going.

2) “Suppose that such a situation happened, during the execution of work, a polyethylene pipe broke on a stone, wrinkled, or even worse. Will defects be visible in production? ”

The question is not clear. Defects “worse” in the performance of work, of course, will be visible, especially when starting inspection.

These documents still apply here (do not forget to pay attention), this is actually the answer to your question:

According to SNiP 2.04.02-84 * p. 8.53 .: “Crossings of pipelines under the railways of categories I, II and III, the general network, as well as under the roads of categories I and II should be accepted in CASES, while, as a rule, provide for a CLOSED way of performing work. When substantiating, it is allowed to provide for the laying of pipelines in TONELLI. Under the rest of the railways and roads, pipelines can be arranged without cases, while, as a rule, STEEL pipes and an OPEN way of doing work should be used. ”

So, you look at your category of road. You may have to put the case, you did not indicate what kind of terrain you have there. Here's to help you:

Category I, II - highways of national importance. The traffic intensity reaches up to 6 thousand cars per day for 1 category and from 3 thousand for 2 categories.
Category III - republican and regional routes - 1-3 thousand cars per day.
Category IV, V - local significance, here from 200 to a thousand cars per day.
 
Also read this document here - SP 40-102-2000 and the "Methodological manual for the design and installation of pipes made of polyethylene." In general, they created so many SNIPs and recommendations that theoretically, subject to the materials and depth, you can find a loophole and not use the sleeve on ordinary local roads. But, most likely, you will not be allowed to do this, and we do not recommend it, nevertheless, with a case you will protect yourself from frequent repairs, which entail many financial and administrative consequences. You can often agree, but it’s better to do the best.

3) “During operation, a defect has occurred and a pipe section needs to be replaced”.

The answer to this question will contain both the initial tolerance for installation and subsequent repair. Let's look at a more serious document than the SNIP. This is the Federal Law of November 8, 2007 N 257-FZ (as amended on 12/27/2018) “On Roads and Road Activities in the Russian Federation and on Amending Certain Legislative Acts of the Russian Federation”.

Article 19. “Laying, reorganization, transfer of utilities, their operation within the boundaries of the right of way and roadside lanes of roads” (I will slightly cut the text of the law for your convenience):

Clause 2 states that the laying, relocation or reorganization of utilities, as well as their operation in places where roads pass, is animated by the owners of communications and at their expense on the basis of an agreement concluded with the owner of the road and on the basis of a building permit issued to you, issued in compliance with the urban planning code of the Russian Federation (in case this permission is required, you need to check with the appropriate organizations, according to the type of your road and other factors).

2.1 During the preparation of the project for the transfer, reconstruction, puncture (hereinafter, for convenience, the RFP) of such works, the place of communication is agreed with the road owners (do not forget, in writing - this is your guarantor).
3. Repeat paragraph 2, indicating that a building permit is required containing the conditions and requirements for the contractor.
4. A building permit is issued by the Federal Law on Investments or a subordinate self-government body.

Well and further, that everything should be supported by agreements and permits, and an unauthorized RFP threatens with the liquidation of utilities, payment of damage, and so on.

That is, if you intend to replace the pipe section, as well as laying it, you need the approvals mentioned above and compliance with the “TTK. Laying engineering networks through the carriageway of roads and railways. TYPICAL TECHNOLOGICAL CARD. Technological map for laying engineering networks through the carriageway of automobile and railway roads. ”

What else can I advise. This replacement item can also be found in the contract that you will conclude with a government agency or road owner. The contract should be read very carefully. I can’t tell you how you’ll ideally be, specifically in terms of materials, depth and other things, because I don’t know all the operating conditions, starting from the passability of the road, ending with the type of soil and materials for pipes. In general, such design work is best entrusted to specialists with their on-site visit with equipment and an assessment of the condition of the infrared installation site. It won't be that expensive.