Flowcharts are not required. You just need a process consistent with your procedures. How you document the process/procedure is up to you (so long as it does make sense).
I am going to add: Since this is in the ISO9000 forum, my answer only applies to ISO9001. Other standards may actually require flowcharts (I avoid automotive and medical for a reason )
work instructions are only necessary for 'value-added' operations
I would not agree. The way I look at it, work instructions are only necessary if, well, they're necessary to ensure a process is done correctly each time. This could be for order of steps (if that's critical) or if a process is so complex it needs to be broken down. I can also use work instructions to provide additional information about steps (for reference).
I see a lot of companies that take the "more is better" approach, documenting everything they do. Employees can get overly-burdened and start ignoring the plethora of documents.
One other thing: why are YOU writing work instructions (assuming you're not the process owner)? I think this is another mistake companies make, having someone (typically in 'quality') write work instructions that they're not actively involved in (often because someone other than the process owner thinks a WI is needed).
No flowcharts are specified in the ISO 9000 series.
Procedures (may include instructions) are meant to be documented sufficient for competent workers to plan and operate each process that is determined to be necessary to fulfill requirements.
Tasks within any of these processes may be mistake-proofed so they cannot be done wrongly and require little documentation.
Documentation may include: software code, flowchart, text, photographs, drawings, etc.
The documented parts of many management systems comprise deployment flowcharts linked to the necessary instructions and forms.
Allow your management system documentation to grow detail as and where needed but also keep it pruned of unnecessary detail.