Why Do Design Firms Decide on Pipe Selection?

In the design of water supply systems for construction projects, it is often the design firm that makes the final call on the material of the pipes, their diameter, and the type of connection used. This raises the question: What criteria do design firms use to determine how a pipe should be selected? What considerations are behind these decisions? Today, we’ll explore this topic.
What Exactly Are Design Institutes Selecting?
Pipe selection may seem simple, but it actually involves a comprehensive assessment across multiple dimensions. The design institute’s task is to find the optimal solution that balances safety, economy, constructability, and service life.
First, codes and standards are the baseline. Any selection must first pass the “compliance” test. The National Architectural Standard Design Atlas 10S407-2 provides detailed regulations specifically for the installation of thin-walled stainless steel pipes in building water supply systems. It sets clear parameters for pipe nominal sizes ranging from DN10 to DN300, operating pressures not exceeding 1.6 MPa, and temperature ranges from -10°C to 100°C. When selecting pipes, design institutes must ensure that pipe specifications fall within these standard parameters for the drawings to pass review.
Second, the application determines the material. Water quality conditions and environmental requirements vary significantly across different projects. For cold-water pipes in ordinary residential buildings, 304 stainless steel is sufficient; however, in coastal areas, for hot spring water supply to households, or for hot water distribution—where chloride content in the water is higher—316L is the correct choice. The addition of molybdenum significantly enhances its resistance to pitting corrosion in chloride-containing environments. Design institutes must match the appropriate material grade based on the water quality report and usage scenario for the project location.
Third, pressure determines wall thickness. The pressure requirements for pipes in high-rise buildings and ordinary residential buildings are completely different. For a DN20 pipe, there is a significant difference in pressure-bearing capacity between wall thicknesses of 1.0 mm and 1.2 mm. Design institutes calculate the appropriate wall thickness grade based on the building height and system operating pressure—excessive thickness leads to waste, while insufficient thickness creates safety hazards. Currently, stainless steel water pipes are generally classified by wall thickness into S1, S2, and S3 grades; the lower the number, the thicker the wall. Designers can select the appropriate grade based on specific requirements.
Fourth, construction conditions influence the selection. Is there sufficient workspace on-site? What are the dimensions of the pipe shafts? Is an open flame required? These factors all influence the selection decision. For example, in renovation projects for older buildings, where pipe shaft space is limited and residents’ daily lives cannot be disrupted, traditional welding methods are simply impractical. In contrast, the press-fit connections of thin-walled stainless steel pipes require only a single squeeze with a hydraulic press—no open flame is needed, and installation is quick—making them clearly advantageous in such scenarios.
Fifth, calculating the total cost over the entire lifecycle. Design institutes do not base their selections solely on the purchase price; instead, they calculate the total cost over a 70-year lifespan. Stainless steel water pipes can last over 70 years, essentially matching the lifespan of the building itself. Ordinary pipes, on the other hand, require excavation and replacement after just 20 to 30 years, and the costs associated with breaking through walls, water outages, and disruption to residents far exceed the price difference between the pipes themselves. This is especially true for water supply systems buried within walls, where replacement is extremely costly. Design institutes must therefore balance initial investment against long-term maintenance costs.
How significant is the impact of a design institute’s material selection?
A single recommendation from a design institute directly determines:
What developers procure—the materials and specifications marked on the drawings serve as the basis for tendering and procurement
How contractors install the system—connection methods, bracket spacing, and pressure testing standards are all specified in the design specifications
Residents’ water quality for decades to come—selecting the right pipes ensures stable water quality and maintenance-free operation; if the wrong choice is made, rusty water, leaks, and repeated repairs will follow in quick succession. Precisely for this reason, the participation of design institutes is indispensable in high-level forums and standard-setting efforts within the stainless steel water pipe industry—they serve as the crucial bridge that translates product standards into engineering practice.
Implications for Purchasers and Property Owners
If you are a developer or property owner, there are three key points to note when faced with a design institute’s material selection recommendation:
Do not lightly “optimize” the material—design institutes have their reasons for selecting 316L; arbitrarily downgrading to 304 may sow the seeds of future problems.
Pay attention to the choice of connection methods—even with the same stainless steel pipe, press-fit, ring-crimp, and welded connections are suitable for different scenarios; do not focus solely on unit price.
Verify the applicable standards—proper product selection will always specify the GB/T standard number, which serves as the basis for quality traceability.
Conclusion
Pipe selection may seem like just a few lines of notation on a drawing, but it is actually a comprehensive balancing act involving safety, economy, and longevity. Design institutes use codes as their yardstick, application scenarios as their mirror, and the full lifecycle as their ledger, ensuring the quality baseline of a building’s water supply is secured before construction even begins. For Wangkun, gaining a spot in design institutes’ selection processes relies not on low prices, but on rigorous compliance with standards, a reputation for reliable quality, and a comprehensive product line suited to diverse scenarios.
Choose the right pipe, and enjoy peace of mind for decades. The expertise of design institutes deserves to be recognized.