## 6 Discussion and Conclusions  
A comparison between an elbow buried in the ground and one anchored in a massif concrete was presented, showing the advantages of the solution of the elbow anchored in concrete. Using MEF, the stresses and strains that appear in the elbow-massif anchorage assembly, as well as in the pressurized pipe of the entire water supply network were determined. From the analysis of the obtained results we can formulate the following conclusions:  
* The maximum stress the concrete massif (Figure 16) was: \(\sigma_{\text{max}}=2.035 MPa<\sigma_{a}=20 MPa\) so that the concrete massif will not be destroyed due to the existing load;
* The maximum stress in the elbow was \(\sigma_{\text{max}}=3.643 MPa<\sigma_{a}=21.9 MPa\) so that the elbow will not be destroyed due to the working demands;
* The plastic deformation in the elbow (Figure 17), at stretch, max 0.228% << 840% which is the specific elongation at break for HDPE [36];
* The comparison between elbow DN 315 buried in the ground and elbow DN 315 anchored in concrete mass, presented in Figures 19-24, where the values of tension and deformation are shown in soil and concrete, justify anchoring the elbow in the concrete massif. The results obtained during the work can be useful to a designer in the case of building a water supply network. They refer to pipes made of HDPE, a wide material used in practice. For the same pipe size, but coming from different manufacturers, a user can make the difference, not only based on the price but knowing the material characteristics resulting from mechanical tests. The paper presented very useful information for specialists who use polyethylene pipes. The results of the work can be materialized in:  
* The proposal of quality assurance and control systems for receiving pipes, which will comply in all respects with the conditions of the reference standards;  
Figure 31: Elbow DN 315 after cracking. * Elaboration of quality control procedures of the companies that manage the water networks, with the right of these companies to control or try the products they purchase during any stage of their manufacture, which can affect the quality of the products and also the possibility of testing the raw materials used in the manufacture of pipes or fittings;
* Elaboration of storage techniques of all the information attesting the quality of the product delivered by a certain supplier and the possibility of comparing price/quality analysis, but also the knowledge of the mechanical characteristics, for similar products from different suppliers;
* Introducing in the quality system the mention \"the obligation of the supplier of plastic pipes to present the regression diagrams of the pipe material\";
* The digital map of the network and the study of rings with specialized software (EPANET, WATERCAD);
* Requesting an express requirement of the beneficiary of the plastic pipe--in the manufacture of the batch of pipes, molds, and samples of the same material as one of the pipes are made, known that for mechanical tests, the samples must have a certain form [36]. The obtained results and their benefits can be transferred to the designers of water supply networks, networks that are found in most localities in the areas of the modern world. Conceptualization, S.V., M.M., M.L.S. ; methodology, S.V., D.D.S. ; software, D.D.S. and M.L.S. ; validation, S.V., M.M. and C.C. ; formal analysis, S.V. ; investigation, D.D.S. and M.L.S. ; resources, D.D.S., S.V. and C.C. ; data curation, D.D.S., M.L.S. ; writing--original draft preparation, D.D.S. and M.L.S. ; writing--review and editing, S.V., M.M. and C.C. ; visualization, C.C. ; supervision, S.V., M.M. ; project administration, S.V. ; funding acquisition, D.D.S., S.V. All authors have read and agreed to the published version of the manuscript. This research was funded by WATER Company, Brasov. We want to thank the reviewers who have read the manuscript carefully and have proposed pertinent corrections that have led to an improvement in our manuscript.