Stainless Steel Pipe Schedule Chart: SCH 5, SCH 10 and SCH 40 Explained

Stainless Steel Pipe Schedule Chart: SCH 5S, SCH 10S and SCH 40S Explained

Stainless steel pipe schedule identifies wall thickness for a given nominal pipe size.

For stainless steel piping, buyers commonly see SCH 5S, SCH 10S and SCH 40S. A higher schedule usually means a thicker wall for the same NPS.

Schedule does not define the stainless steel grade. It also does not directly define the allowable working pressure.

Grade, temperature, design code and service conditions must also be considered.

What Does Pipe Schedule Mean?

Pipe schedule is a dimensionless designation associated with pipe wall thickness.

It is not the same as wall thickness in millimeters. For example, SCH 40S does not mean a 40 mm wall.

The actual wall thickness depends on the nominal pipe size.

For a given NPS, changing from SCH 5S to SCH 40S normally increases wall thickness. The outside diameter stays the same. The inside diameter becomes smaller.

SCH 5S vs SCH 10S vs SCH 40S

Item	SCH 5S	SCH 10S	SCH 40S
Relative Wall	Thin	Medium	Thicker
Material Weight	Lower	Higher than 5S	Higher
Internal Diameter	Larger for the same NPS	Intermediate	Smaller for the same NPS
Typical Selection	Light-duty systems where permitted	General process and industrial piping	Applications requiring a heavier wall

Important: these descriptions are general selection directions. Schedule alone is not a pressure rating.

Stainless Steel Pipe Schedule Chart

The following table shows common ASME B36.19 stainless steel pipe dimensions. Values are nominal dimensions.

NPS	Outside Diameter mm	SCH 5S Wall mm	SCH 10S Wall mm	SCH 40S Wall mm
1/2″	21.34	1.65	2.11	2.77
3/4″	26.67	1.65	2.11	2.87
1″	33.40	1.65	2.77	3.38
1-1/4″	42.16	1.65	2.77	3.56
1-1/2″	48.26	1.65	2.77	3.68
2″	60.33	1.65	2.77	3.91
2-1/2″	73.03	2.11	3.05	5.16
3″	88.90	2.11	3.05	5.49
4″	114.30	2.11	3.05	6.02
6″	168.28	2.77	3.40	7.11
8″	219.08	2.77	3.76	8.18

Why Does the “S” Matter?

For stainless steel pipe, ASME B36.19 uses schedule designations such as 5S, 10S and 40S.

The suffix “S” distinguishes B36.19 stainless steel pipe dimensions from the schedules in ASME B36.10.

Some wall thicknesses are the same between the two standards. Others are different.

For this reason, buyers should state the exact dimensional standard on the purchase order. Writing only “SCH 10” can create unnecessary ambiguity for stainless steel piping.

Does a Higher Schedule Mean Higher Pressure?

A thicker wall can support higher pressure under otherwise comparable conditions. But schedule itself is not a pressure rating.

Allowable pressure depends on several factors.

• Stainless steel grade

• Design temperature

• Outside diameter and wall thickness

• Material allowable stress

• Weld joint factors where applicable

• Corrosion or mechanical allowance

• Applicable piping design code

A piping engineer should confirm the required wall thickness for pressure service.

ASTM A312 and ASME B36.19: What Is the Difference?

These standards perform different jobs.

Standard	Main Purpose
ASTM A312/A312M	Material and manufacturing specification for applicable austenitic stainless steel pipe
ASME B36.19	Standardizes dimensions of welded and seamless wrought stainless steel pipe

An RFQ may therefore specify both.

How to Choose SCH 5S, 10S or 40S

Requirement	Selection Direction
Minimum weight and thin wall	Evaluate SCH 5S where permitted by the design
General industrial piping	SCH 10S is a common option, subject to design requirements
Greater wall thickness	Evaluate SCH 40S
Pressure-critical system	Calculate required wall thickness under the applicable design code

What Buyers Should Include in an RFQ

• Stainless steel grade: TP304L, TP316L or other specified grade

• Material standard

• Seamless or welded construction

• NPS or outside diameter

• Schedule or exact wall thickness

• Length and quantity

• Dimensional standard such as ASME B36.19

• Surface and end preparation if required

• MTC and inspection requirements

FAQ

What is the difference between SCH 10S and SCH 40S?

SCH 40S generally has a thicker wall than SCH 10S for the same nominal pipe size. This reduces the internal diameter and increases material weight.

What does SCH 5S mean?

SCH 5S is a thin-wall schedule designation used for stainless steel pipe dimensions under ASME B36.19.

Is SCH 40S the same as SCH 40?

Not in every pipe size. ASME B36.19 uses the “S” suffix for stainless steel schedules. Some dimensions coincide with B36.10, while certain sizes differ. Always confirm the applicable dimensional standard.

Does pipe schedule change the outside diameter?

No. For the same NPS, the standardized outside diameter remains the same. Increasing the schedule increases wall thickness and reduces the inside diameter.

Is Schedule 40S a pressure rating?

No. Schedule identifies wall thickness. Pressure capability must be determined using the material, temperature, dimensions and applicable piping design code.