1. **What is the difference between Schedule 40 and 40S pipes?**
* The main difference is wall thickness and typical application. Schedule 40 (SCH 40) is the standard wall thickness designation for pipes of a given size and material. Schedule 40**S** (SCH 40S) is a specific *stainless steel* pipe schedule. While SCH 40S pipes have the *same pressure rating* as standard SCH 40 carbon steel pipes of the same size, SCH 40S pipes generally have a *slightly thinner wall* than standard SCH 40 stainless steel pipes. Essentially, SCH 40S is the "standard weight" designation specifically for stainless steel, optimized for corrosion resistance while maintaining pressure rating.
2. **Which is better, seamless or ERW pipe?**
* Neither is universally "better"; the choice depends on the application. **Seamless pipe** has no welded seam, making it generally stronger, more reliable for high-pressure, high-temperature, or critical service (like hydrocarbons), and less prone to corrosion or failure along a weld line. **ERW (Electric Resistance Welded) pipe** has a longitudinal weld seam. It is typically more cost-effective, available in larger diameters, and perfectly suitable for many lower to medium pressure applications (like water lines, structural uses, fencing). ERW quality has improved significantly, but seamless remains the choice for the most demanding services.
3. **Is schedule 40 conduit flexible?**
* **No, Schedule 40 conduit is not flexible.** It is manufactured as rigid lengths of pipe (typically 10 or 20 feet). While a *very small* amount of bending might be possible with significant force due to its thinner wall compared to rigid metal conduit (RMC), it is **not designed or rated for bending** in the field like Electrical Metallic Tubing (EMT) or flexible conduit. Bending it would likely kink or damage it.
4. **Is Schedule 40 considered rigid?**
* **Yes, Schedule 40 conduit is classified as a type of rigid conduit.** Specifically, PVC Schedule 40 conduit is defined as **Rigid Polyvinyl Chloride Conduit (PVC)** in the US National Electrical Code (NEC). It provides a rigid, non-flexible raceway for protecting electrical wires.
5. **What is the difference between Schedule 40 and conduit?**
* "Schedule 40" refers to a **wall thickness standard** (defined by dimensions, not pressure rating for conduit). "Conduit" refers to a **purpose**: a tube or pipe specifically designed to route and protect electrical wires or cables.
* **Schedule 40 *Pipe***: Primarily designed to carry fluids or gases under pressure. Its dimensions and pressure ratings are standardized (e.g., ASTM A53, A106 for steel; ASTM D1785 for PVC). Wall thickness is relatively heavy.
* **Schedule 40 *Conduit***: Specifically designed for electrical wire protection. While it uses the "Schedule 40" dimensional standard (outer diameter and wall thickness similar to Schedule 40 PVC *pipe*), its primary purpose is **not pressure containment**. It meets different standards (e.g., UL 651, NEC Article 352 for PVC) focused on crush resistance, impact resistance, flame retardancy, and suitability for electrical installations. Fittings and joining methods are different from pressure pipe. It's important to use conduit specifically listed and marked for electrical use.
**In Summary:**
* SCH 40S is thinner-wall stainless steel with the same pressure rating as SCH 40.
* Seamless pipe is stronger for critical service; ERW is economical for standard service.
* Schedule 40 conduit is rigid, not flexible.
* Schedule 40 conduit *is* a type of rigid conduit (specifically Rigid PVC Conduit).
* "Schedule 40" defines wall thickness; "Conduit" defines the purpose (electrical protection). Schedule 40 Pipe carries fluids under pressure; Schedule 40 Conduit protects electrical wires.
