Two pipes with the same diameter can have completely different schedules and working pressures. Let’s examine the concept of pipe schedule and the difference in their working pressures.
Place two pipes side by side, both with the same outside diameter; however, one is sufficient for ordinary building water pressure, while the other is required for a high-pressure gas transmission line. The difference between them lies not in the diameter, but in what is called the pipe schedule.
What Is Pipe Schedule
Schedule is a standard number that determines the wall thickness of a pipe at a specified diameter. The most common schedules on the market are Schedule ۴۰ and Schedule ۸۰; with the same outside diameter, Schedule ۸۰ has a thicker wall than Schedule ۴۰. The higher the schedule, the thicker the wall, the greater the weight, and the higher the working pressure it can withstand.
Two pipes can have the same diameter but completely different schedules and working pressures.
Comparison of Common Schedules
| Schedule | Relative wall thickness | Working pressure | Common application |
|---|---|---|---|
| Schedule ۲۰ | Thinner | Lower | Light-duty and low-pressure applications |
| Schedule ۴۰ | Medium | Medium, sufficient for most general applications | Water supply and ordinary building plumbing; the most widely used choice on the market |
| Schedule ۸۰ | Thicker | Higher | Industrial applications and lines with higher-than-normal pressure |
Why This Matters for Sales
If you ask the customer only about the pipe diameter and overlook the schedule, you may sell a low-schedule pipe for a high-pressure service, which may cause problems later; or, conversely, recommend a higher and more expensive schedule than the actual application requires for a simple use. Asking about the customer’s application and required pressure is precisely the question that distinguishes a proper sale from a risky one.
For warehousing as well, since Schedule ۴۰ is the most widely used choice in the construction market, keeping a larger volume of this schedule in common sizes usually provides the highest turnover for your inventory investment.
An Additional Point
The schedule on a bare pipe is usually identified by a color mark or a stamp on the body; make it a habit to verify this mark before selling, especially when two different schedules are stored side by side and their appearance is very similar.
Frequently Asked Questions
رده لوله (Schedule) یعنی چه؟
رده، عددی است که ضخامت جدار لوله را استاندارد می‌کند. هرچه رده بالاتر باشد، جدار ضخیم‌تر و فشار قابل‌تحمل لوله بیشتر است؛ رایج‌ترین رده‌ها ۴۰ و ۸۰ هستند.
فرق لوله رده ۴۰ و رده ۸۰ چیست؟
در قطر بیرونی یکسان، رده ۸۰ جدار ضخیم‌تری نسبت به رده ۴۰ دارد و فشار کاری بیشتری تحمل می‌کند؛ به همین دلیل هم سنگین‌تر و هم گران‌تر است.
در بازار ساختمانی معمولی، کدام رده پرمصرف‌تر است؟
رده ۴۰ برای اکثر کاربردهای عمومی مثل آبرسانی و لوله‌کشی ساختمانی معمولی کافی و پرمصرف‌ترین انتخاب است. رده ۸۰ بیشتر برای فشار بالاتر و پروژه‌های صنعتی به‌کار می‌رود.
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